Robert Downey Jr. kept food hidden all over the lab set, and apparently nobody could find where it was, so they just let him continue doing it. In the movie, that's his actual food he's offering, and when he was eating, it wasn't scripted, he was just hungry.
There were very few times that everyone was in town at once, but on one night when they were, Chris Evans sent them all a text message simply saying "Assemble" (the tagline to the movie), prompting a night out on the town. Clark Gregg has stated that this is his favorite text message that he has ever received.
Reportedly, a scene was filmed, where during the final battle, Captain America saves an old man trying to protect his grandchildren. He tells him to "Get them to cover", but as he walks away, the old man asks him "Cap, is that really you?" He turns and, noting the man's World War II veteran lapel pin, trades salutes with him. As Captain America sprints away, the children ask their grandfather, "Do you know him?", and he replies "We ALL know him".
Robert Downey Jr. asked the Marvel Production Manager permission to take away the letter "A", that was on the Stark Tower with him, but he declined. However, on his next birthday, the manager gave it to him as a gift.
(at around 46 mins) After Thor takes Loki off the Quinjet down on the mountain side, two large ravens fly by them as they are talking. In Norse mythology, Thor's father and Loki's blood brother, Odin, had two ravens, Huginn and Muninn, who would bring Odin information from Midgard (Earth). (This film repeats the "family tree" error from the original Marvel comics.)
Joss Whedon explained that two of the founding Avengers members, Ant-Man and Wasp, were cut from the script, because the film had too many characters. Also, the screenwriters didn't want Ant-Man in the Marvel Cinematic Universe, until his movie was released.
(at around 54 mins) According to Joss Whedon, the "That man is playing Galaga!", line was ad-libbed by Robert Downey Jr., and worked so well, that Whedon decided to dub in an image of Galaga on "that man's" console, as the scene's punchline.
(at around 55 mins) Chris Evans was unsure about his character's line, "I understood that reference!", because he was worried that it would make audiences think that his character was unintelligent. However, he was quickly comforted after he watched the movie with an audience, and he saw that they found the line humorous, as opposed to stupid.
(at around 1h 11 mins) The laboratory scene, where Bruce Banner explains how he once attempted to commit suicide by shooting himself in the mouth is a direct reference to a deleted scene from The Incredible Hulk (2008), where Edward Norton's Bruce Banner tried to commit suicide in this manner, out in the middle of Alaska's wilderness, only to be stopped by his transformation into the Hulk.
The final end credit scene was added after Robert Downey Jr. encouraged a scene re-write. After Tony Stark falls back to Earth, he originally awakens and asks, "What's next?" Robert Downey, Jr. thought the line could be more interesting, and the idea of going to a local shawarma restaurant was born. The scene was added one day after the global premiere. Since then, shawarma sales in Los Angeles, St. Louis, and Boston have reportedly skyrocketed.
Chris Hemsworth had to increase and expand his food intake in order to maintain the physique he built up for Thor (2011), consisting of chicken breasts, fish, steak, and eggs every day (Hemsworth said he had to consume "his body weight in grams of protein.").
According to Director Joss Whedon, the original cut of the movie was over three hours long. About thirty minutes of the excised footage are included on the Blu-ray, most of which revolves around Steve Rogers (Captain America) struggling to adjust to the modern world. Chris Evans announced later that these deleted scenes would be used for Captain America: The Winter Soldier (2014).
Samuel L. Jackson's role as Nick Fury in this film makes him the second actor (after Hugh Jackman, who has appeared in all of the X-Men movies) to play the same comic book character in five different movies.
The Pentagon said they "couldn't reconcile the unreality of S.H.I.E.L.D., and our place in it." (to elaborate, it's left ambiguous as to whether S.H.I.E.L.D. is a national or international agency, and the Pentagon didn't like the implication that the U.S. Military would answer to anyone, other than the U.S. government) and thus declined involvement in this movie. However, the U.S. Army did give their involvement.
Samuel L. Jackson's Nick Fury is from the Ultimate Marvel Universe, created in 2000 to re-imagine, and update the Marvel heroes for the twenty-first century. Fury's likeness was actually based on Jackson, who gave Marvel permission to do so. Subsequently, based on that likeness, and his star power, Jackson was cast as Fury for all Marvel Cinematic Universe films, starting with Iron Man (2008).
Joss Whedon suggested to Marvel, that there should be a bigger villain plotting behind-the-scenes, which enabled Loki to conquer the Earth, and that someone should be Thanos the Mad Titan. The executives just rolled with it.
Sound Editor Christopher Boyes has stated, that he went through a complicated process to craft the Hulk's voice. The final product "turned out to be (a combination of) Mark Ruffalo, some Lou Ferrigno, and a little bit of me and two people from New Zealand."
Tom Hiddleston spoke of his role as Loki in an interview by saying, "I can tell you that it's all of them against me. I am the supervillain. So it's Iron Man, the Incredible Hulk, Captain America, Thor, Hawkeye, Black Widow, and Nick Fury forming a team, because I've gotten so bad ass."
Joss Whedon had earlier been considered to direct X-Men (2000) in the 1990s. A big fan of the X-Men, he even wrote a script, from which only two lines made it into the film. He wrote the story "Gifted" for "Astonishing X-Men", which became the basis for X-Men: The Last Stand (2006).
There are two spoken references to the early Incredible Hulk comic books. When Captain America is giving orders, he says "Hulk, smash", a catchphrase uttered by the Hulk in the comics, as well as The Incredible Hulk (2008). After the Hulk thrashes Loki, he says "Puny god", a reference to another oft-repeated Hulk phrase, "Puny humans".
(at around 53 mins) According to Joss Whedon's commentary, Bruce Banner's saying of Loki, "You can smell crazy on him", was a set-up for when the Hulk faces off against Loki in Stark Tower. Originally, Loki was going to make multiple versions of himself, and the only way the Hulk was going to discern where Loki was, was to smell them. Only the real Loki would have a scent.
Tony Stark casually refers to three of the other main characters, Loki, Thor, and Hawkeye, as either movie characters, or movie titles. He calls Loki "Reindeer Games", Thor "Point Break", and Hawkeye "Legolas".
(at around 56 mins) After Loki is brought on board the Helicarrier, Tony Stark can be seen wearing a Black Sabbath t-shirt. Black Sabbath is better known for their song "Iron Man". Although the song was not originally associated with the Marvel Comics character, it has since been referenced in the comics, and the end of Iron Man (2008), when Tony quotes the lyrics, "I am Iron Man".
Originally, Joss Whedon had not intended the film to include supporting characters from the heroes' individual films, reasoning, "You need to separate the characters from their support systems, in order to create the isolation you need for a team." However, he eventually decided to cast Stellan Skarsgård, Paul Bettany, and Gwyneth Paltrow (Paltrow was cast at Robert Downey Jr.'s insistence).
Edward Norton was originally set to reprise his role from The Incredible Hulk (2008), but negotiations between him and Marvel Studios broke down. Norton was replaced with Mark Ruffalo, who had also been considered for the role in the prior movie.
(at around 1h 14 mins) When Natasha Romanoff, a.k.a. Black Widow, and Bruce Banner are blasted to a lower deck of the Helicarrier, it triggers Banner's transformation into the Hulk. As he is transforming, he falls from a platform to the floor. On the floor is painted "WARNING: CONTENTS UNDER PRESSURE" with small arrows, which happen to be pointing to Banner.
Robert Downey Jr. initially pushed Joss Whedon to make Tony Stark the lead: "I said, I need to be in the opening sequence, Tony needs to drive this thing. He was like, okay, let's try that. We tried it, and it didn't work, because this is a different sort of thing, everybody is just an arm of the octopus."
The filmmakers secured the rights from Columbia Pictures to feature OsCorp Tower, from The Amazing Spider-Man (2012) in New York City. Unfortunately by then, digital rendering of the skyline was already complete, and it could not appear.
According to Joss Whedon, the film is strongly influenced by the early 1960s Avengers comics, of which he was a fan while growing up: "In those comics, these people shouldn't be in the same room, let alone on the same team, and that is the definition of family."
(at around 2h) When filming the scene of Loki yelling at the Hulk, Tom Hiddleston had a rope tied to his leg, and since the Hulk is just CGI, when the rope was pulled, it would appear that the Hulk had grabbed him. Tom knew it was going to be pulled during the speech, but he didn't know when, so that he wouldn't be anticipating it.
(at around 55 mins) Tony Stark tells Bruce Banner that he admires his work on anti-electron collisions. When electrons and anti-electrons (also known as positrons) collide, they annihilate each other and high-energy photons, or gamma rays (the fictional means, by which Bruce Banner became The Incredible Hulk) are produced in their place.
This was the highest grossing film of all time not directed by James Cameron (it was third under Titanic (1997)'s second place and Avatar (2009)'s first). It has since been replaced by Star Wars: The Force Awakens.
Mark Ruffalo claims to be the only actor, to-date (2012), to play both The Hulk, and Bruce Banner in the same movie. Technically, both Eric Bana and Edward Norton had done motion-capture work for their respective Hulks, but Ruffalo is the first actor to perform the Hulk live on-set via performance capture. What is most certainly a confirmed "first" for Ruffalo's Hulk, however, is clearly defined chest hair (of which Ruffalo has plenty). That has absolutely never been done before in any portrayal of the Hulk, whether it be live, animated, or drawn.
In the movie, Captain America is a founding member. In the comics, Captain America was unfrozen in Avengers #4, when he was accidentally discovered, when the team was looking for Namor the Sub Mariner.
Lou Ferrigno contributed to the voice of the Hulk in this film. He has played the Hulk in almost every live-action version since 1978: he played the Hulk in the television series The Incredible Hulk (1978), and its subsequent three television specials. He voiced the Hulk in the big-screen The Incredible Hulk (2008), in which he also played a security guard. He also played a security guard in Hulk (2003). He also has voiced the Hulk in various animated productions.
(at around 1h 40 mins) Tony Stark describes his group as "Earth's mightiest heroes, that kind of thing." This refers to the famous tagline that has been featured on the cover of "The Avengers" comic books since its 1963 debut. The phrase was also used as the subtitle for The Avengers: Earth's Mightiest Heroes (2010), the animated series which began a airing one year prior to the live-action Avengers film.
According to Joss Whedon, the arrangement of the monitors on the Helicarrier bridge, were arranged to resemble the wings of the S.H.I.E.L.D. logo. The eagle head can actually be seen at the foot of the conference round table, at the end of the film, when repairs are being made.
Joss Whedon supposedly had a detailed backstory for Hawkeye written up, but was unable to even reference any of it, due to time constraints. During the early planning stages, Hawkeye was envisioned to be depicted as a circus performer, trained by supervillains, who manipulate him into fighting the team, essentially a modernized version of his 616 origin story. At another point, he was planned to debut in Iron Man 2 (2010) as an Agent of S.H.I.E.L.D., who works closely with Natasha Romanov, a.k.a. Black Widow, and Nick Fury.
According to Vulture, this is the amount of screentime each hero has in the film: -Steve Rogers/Captain America: 37:42. -Tony Stark/Iron Man: 37:01. -Natasha Romanov/Black Widow: 33:35. -Bruce Banner/The Hulk: 28:03. -Thor: 25:52. -Clint Barton/Hawkeye: 12:44.
Thor spends most of this movie in his Asgardian armor, but with bare arms, a nod to his early appearances in the comics. During his time on the Helicarrier, he is also seen without his cape, an allusion to his Ultimate Comics appearance.
The name "chitauri" originates from Zulu mythology, and is used to describe a "serpent race from the sky." Mark Millar, the creator of "The Ultimates", took the name from the writings of David Icke, who argues that these "chitauri", are in fact aliens, bent on dominating humanity.
According to Mark Ruffalo, Edward Norton mainly didn't like that Bruce Banner was struggling with his issues of the Hulk all over again, when at the end of The Incredible Hulk (2008), it seemed as though Banner had actually accepted it, and thus, the Avengers movie wouldn't really be developing Banner's character much.
(at around 24 mins) Stark Tower stands where the MetLife building should be. The digital model of the tower that Pepper is looking at shows that the bottom third of the tower retains the shape of the MetLife building with the rest of the floors redesigned.
According to the Visual Effects Supervisor, Joss Whedon disliked Iron Man's "tinkerbell pose" when flying. So he insisted that in this movie, the suit be equipped with a jetpack. This would allow his hands (gauntlets) to be free, which, in turn offered those great "cowboy" poses, that were seen in the film.
Robert Downey Jr. thought the scene when Iron Man regains consciousness could use a little snappier dialogue, so he requested that Joss Whedon add some. One of the ones that made the cut (the Shawarma reference) is influenced by Nicholas Brendon's (Xander from Buffy the Vampire Slayer (1996)) interview. Nicholas mentions, "Would anyone like to go get some Shawarma?"
Since this film and Iron Man Three (2013) were originally part of a six-picture deal with Marvel and Paramount before the distribution rights were transferred to Walt Disney Pictures, it's the Paramount logo that appears in advertising and marketing, as well as the beginning of this film. Although Paramount had no part in the production of this movie, they still received a share of the box-office grosses, based on their original deal with Marvel. No reference to Disney is made, until the very end of the closing credits, where it says "The Avengers" is "Distributed by Walt Disney Studios Motion Pictures."
Tony Stark's Acura roadster is neither the 2012 NSX Concept show car, nor an actual prototype of the 2015 next-generation hybrid Acura NSX. It was custom-designed specifically for the movie, by Honda North America Chief Designer Dave Marek. The "donor car" was a 1991 NSX from Arizona, with two hundred fifty-two thousand miles on its odometer. The interior of the movie car is almost totally stock, and still has the original cassette tape player in the console.
(at around 56 mins) In the film, Bruce Banner references the fact that the last time he was in New York City, he "broke Harlem". This is a reference to _The Incredible Hulk (2008)_, when The Hulk, portrayed by Edward Norton, fights the Abomination in Harlem, New York.
Mark Ruffalo's performance of the Hulk is the first created by motion-capture. Previous live-action versions have either had Bruce Banner and the Hulk be played by separate people (Bill Bixby and bodybuilder Lou Ferrigno), or were key-frame animated.
(at around 19 mins) Nick Fury states to the council that "Phase Two is not ready." Later, when Tony Stark decodes S.H.I.E.L.D.'s secret files, while on the Helicarrier in Bruce Banner's lab, he asks Nick Fury about "Phase Two." This is a nod to the Marvel Cinematic Universe film phases: this film being the end of Phase One, and Iron Man Three (2013) being the beginning of Phase Two.
(at around 1h 30 mins) Harry Dean Stanton, who appears as the janitor who discovers Banner, after he fell from the Helicarrier asks "are you an alien?" Stanton is widely known for his role as Brett in Alien (1979).
An alternate opening and ending frame the movie as a flashback from Agent Maria Hill, allowing them to simultaneously flesh out her dislike towards Fury's methods, yet her undying loyalty to S.H.I.E.L.D.
Cinematographer Seamus McGarvey described the film's look as visceral and naturalistic: "We wanted this to feel immersive, and did not want a comic book look that might distance an audience. We moved the camera a lot on Steadicam, cranes, and on dollies, to create kinetic images, and we chose angles that were dramatic, like low angles, for heroic imagery."
The Chitauri appear in the first story arc of "The Ultimates", an alternate universe retelling of the origins of the Marvel superheroes. In the comics, their leader claims that they go by many names, including Skrulls. It was originally assumed that the reason for using "The Chitauri", instead of "The Skrulls", was because 20th Century Fox owns the rights to the Fantastic Four, and their supporting characters. However, Marvel Studios' President of Production, Kevin Feige, stated in an interview, that the film rights to the Skrulls are not owned by either Marvel Studios or 20th Century Fox. The reason for them not being used, was that Joss Whedon did not want go the route of using shape-shifters in the first film.
Samuel L. Jackson compared his role of Nick Fury to Ordell in Jackie Brown (1997): "He's a nice guy to hang out with, you just don't want to cross him. I tried to make him as honest to the story, and as honest to what real-life would seem."
Mark Ruffalo describes Bruce Banner as "a guy struggling with two sides of himself, the dark and the light; everything he does in his life is filtered through issues of control." He furthermore describes Banner's alter-ego the Hulk as "a loose cannon. He's the teammate none of them are sure they want, it's like throwing a grenade into the middle of the group and hoping it turns out well!"
Seamus McGarvey shot the film in a 1.85:1 aspect ratio, rather than in a 2.35:1, was to cope with the varying heights: "We needed the height in the screen, to be able to frame in all the characters like Hulk, Captain America, and Black Widow, who is much smaller. We had to give them all precedence and width within the frame. Also, the final battle sequence was going to be this extravaganza in Manhattan, so the height and vertical scale of the buildings was going to be really important."
(at around 37 mins) Loki is described as being a King in the world from which he came. Shortly after this, when The Avengers ask for Loki's location in Germany, Loki is said to be at "22 Königstrasse", meaning 22 King Street.
This is the first film in the Marvel Cinematic Universe to debut the revised S.H.I.E.L.D. logo. As compared to the more stylized eagle design on the logo (as seen in the opening scene at the dark energy research facility), the updated logo features a simplified eagle design (as seen on the flight deck, and on the bridge of the Helicarrier). This design will become the default S.H.I.E.L.D. logo, as seen in Captain America: The Winter Soldier (2014), and Marvel's Agents of S.H.I.E.L.D. (2013).
The outdoor scenes, which were supposed to take place in Germany, but were filmed in downtown Cleveland, Ohio, contained numerous Cleveland Historical landmarks including; Tower City, Higbee Building and Casino, the Renaissance Building, and the Soldiers' and Sailors' Monument.
(at around 1h 11 mins) When Banner talks about having tried to kill himself, by putting a bullet in his mouth, but the Hulk spit it out. In the deleted scene of The Incredible Hulk (2008), where Banner goes to kill himself, he clearly never got the chance to shoot himself, since the Hulk starts to appear to stop him. However, in the video game of The Incredible Hulk (2008), the opening cut scene clearly shows Hulk is spitting out the bullet.
Only the paint on Captain America's shield is scratched in the film. In the comics, his shield is made of an adamantium and vibranium alloy, with a third mystery catalyst, and can only be damaged by beings who possess nearly ultimate power, such as Molecule Man, Rune King, Thor, or Thanos with the Infinity Gauntlet. The shield is otherwise impervious.
(at around 27 mins) When Agent Coulson visits Stark Tower, Pepper asks him about the cellist in Portland. Tony is also heard telling Coulson he could fly him to Portland (at around 53 mins). This woman ends up being a plot point for an episode of Marvel's Agents of S.H.I.E.L.D. (2013).
The twelfth film to surpass the one billion dollar mark worldwide, and the tenth to surpass the four hundred million dollar mark in the U.S. It tied with Avatar (2009) and Harry Potter and the Deathly Hallows: Part 2 (2011) for surpassing the one billion dollar mark worldwide in the fastest time (nineteen days), and set the record of surpassing the four hundred million dollar mark in the U.S. (fourteen days).
The film originally opened and closed, with Agent Hill reporting to the World Security Council on the Avengers, and on Fury's decisions, but this was scrapped, because it didn't mesh with the tone of the film.
This is only the second time that Bruce Banner, a.k.a. Hulk, and Thor have appeared together in a movie. They previously appeared together in NBC's television film The Incredible Hulk Returns (1988), which starred Bill Bixby as Dr. David Bruce Banner. He previously performed that same role in the television series of The Incredible Hulk (1978) on CBS.
Two founding members of The Avengers from the comics were left out of this movie: Ant-Man and the Wasp. They were replaced by Hawkeye and Natasha Romanoff, a.k.a. Black Widow, in an attempt to better integrate S.H.I.E.L.D. into the story.
Due to UK copyright issues over the name, Marvel had to release the film in the UK under the name "Avengers Assemble", as there had already been an unrelated film with Sir Sean Connery and Ralph Fiennes released by Warner Brothers under The Avengers name in 1998. That 1998 film itself was based on a UK television action adventure series from the 1960s which starred Patrick Macnee. As Warner Brothers UK owned the copyrighted name, and objected to Marvel using it, Marvel were forced to change the name to "Avengers Assemble" for its UK theatrical and home media release. As film prints and marketing for the Republic of Ireland were handled by Disney UK. They decided to stick with the name change for that territory too, for cost effectiveness reasons.
During the post-credits scene, a large letter "A" can be seen on the wall of the restaurant. While this could be seen as an obvious reference to the Avengers, it is actually a health inspector certificate. The letter grades are similar to an academic grading system, so an "A" would be the best score a food establishment could have.
The "wishbone" section of the Helicarrier, where Banner's lab is located, is referred to in naval architecture as a "well deck". It provides a sheltered docking area, typically used for launching small boats or hovercraft for carrying troops ashore.
(at around 1 min) The opening scene is at the famous radar array in New Mexico from Contact (1997), where they make contact with an alien species. In both movies, the alien is a symbol of man's tiny place in the universe.
The single-engine jet fighters are computer-rendered Lockheed Martin F-35 Lightning IIs. F-35s appear briefly in several scenes, including a sequence of the airplane transitioning from forward flight, to vectored-thrust hover-mode, in order to fire its twenty-five millimeter cannon. The F-35 was still in development at the time, and didn't even have basic combat capability until late 2015.
(at around 1h 45 mins) Enver Gjokaj plays the young police officer, to whom Captain America gives orders, at the beginning of the battle of New York City. He also plays Agent Sousa in Marvel's Agent Carter (2015).
Although S.H.I.E.L.D. possesses futuristic technology, such as the Helicarrier, or the futuristic shuttles, some outdated aircraft can still be seen on the carrier. There is a huge number of Alpha-Jets, a German-French co-production that were put out of service by the German air forces in 1993, as well as showing some AV-8B Harrier II+, the night attack variant of the Sea Harrier, that is recognizable by its stretched nose, and is still in service with the U.S. Marine Corps. Finally, there is the latest and most capable aircraft on board: the F-35 Lightning II, that is about to be put into service by many air forces throughout the world.
In the movie, Samuel L. Jackson and Jeremy Renner reprise their rolls as Nick Fury and Hawkeye, respectively. Both played similar roles in the same movie nine years earlier. In S.W.A.T. (2003), Jackson played Sergeant Hondo Harrelson, a S.W.A.T. team leader charged with assembling a team of individuals to defend against bad guys. Renner played Brian Gamble, an expert marksman, and once a member of S.W.A.T., who uses his skills against his former friend, and S.W.A.T., when the main villain's actions influence him too much, like in this film. S.W.A.T. (2003) also starred Colin Farrell, who played Bullseye, one of the main villains in Daredevil (2003).
The overall premise of the film is very similar to the pilot episode for the animated television series Justice League (2001) (which is based on the DC Comics counterpart). In both story lines, the team of superheroes bands together for the first time, in the wake of a pending alien invasion.
(at around 1h 29 mins) When Fury tells the Avengers of Coulson's death, Tony's arc reactor is not glowing. This is a goof cinematically, but fan theories suggested that his heart is dead like his friend since it glows before and after this scene.
The bridge where Iron Man, Thor, Captain America, Hawkeye, Black Widow, and Hulk fight against Chitauri's army, is the same bridge where J jumps onto a bus full of tourists, while pursuing an alien in Men in Black (1997).
(at around 21 mins) In Captain America's opening scene, he is in a gym, punching a heavy bag. He punches the bag so hard it breaks its chain and falls to the floor. This parallels a similar scene from the "Buffy the Vampire Slayer" episode Buffy the Vampire Slayer: The Gift (2001), also directed by Joss Whedon, in which Buffy hits a heavy bag so hard, its chain breaks, and the bag falls to the floor.
Chinese title for the movie reads "Fu Chou Zhe Lian Meng" (literally, Avengers Alliance), while the online fan base and community like to abbreviate this title as "Fu Lian", which would be homonym to the abbreviation of "Women's Federation" in Chinese. Since it's easier to input this homonym when using common Chinese Pinyin input methods, online forums and communities went on to refer to The Avengers as it.
(at around 48 mins) When Thor attacks Iron Man in the forest, J.A.R.V.I.S. informs Tony Stark that his armor is up over four hundred percent energy. When the camera focuses inside Iron Man's helmet, the real percentage of 475 can be seen. It appears to the left of the screen, close to Tony Stark's cheek.
(at around 55 mins) During the scene where the Avengers are discussing Loki and his sceptre, Captain America gets excited when he understands a reference to flying monkeys, when Fury says how Loki has put Hawkeye and Eric Selvig under his command with the sceptre. This is a reference to The Wizard of Oz (1939), where some of the Wicked Witch of the West's minions are large, winged monkeys. That movie was released in 1939, so Captain America could have seen it before he was frozen. Thor, being from another world, has not seen the film and therefore does not get the reference.
(at around 32 mins) When Agent Romanoff is on the Helicarrier showing Captain Rogers and Bruce Banner around, she's wearing a black jacket and pants with a red shirt underneath signifying the iconic colors of her code name: Black Widow.
Robert Downey Jr. and Mark Ruffalo took on the roles of real-life journalistic heroes in two separate films: Ruffalo as Boston Globe investigative journalist Mike Rezendes in Spotlight (2015), and Downey as Joe Wershba, one of Edward R. Murrow's news team at CBS, who helped to put an end to Senator Joseph McCarthy's anti-Communist crusade, in Good Night, and Good Luck. (2005).
In the beginning of the film, the pistol that Nick Fury and other SHIELD agents are using is the Sig-Sauer P229 DAK, a 40 caliber double-action only pistol which is the standard sidearm of the FBI and the Coast Guard.
As each character is introduced the previous scene references that character. It begins when Fury says to call in the rest of the team, leading to the next scene of Black Widow being called. In that scene she is told to bring in "the big guy", referencing the Hulk. The next scene has her luring Bruce Banner. In the next scene Fury is having a video conference with the World Security Council and says a war is won with soldiers, leading to the next scene with Captain America. In that scene he says the tesseract should've been left in the ocean, leading to the next scene in which Iron Man is in the water.
The film shares its title with The Avengers (1998). However, the 1998 Avengers is based on the classic 1960s spy series, and the lead protagonists John Steed (Ralph Fiennes) and Emma Peel (Uma Thurman) are British Secret Agents. In this film, The Avengers are team of superheroes, brought together and assembled by Nick Fury, Director of S.H.I.E.L.D. Nick Fury, Natasha Romanov, a.k.a. Black Widow, Clint Barton, Phil Coulson, and Maria Hill are Agents of S.H.I.E.L.D.
At the beginning of the first segment when Loki arrives, he starts taking over and Nick Fury grabs the tesseract out of the machine and installs it into a special carrying case. He doesn't get transported as the Red Skull did at the end of Captain America, The First Avenger(2011), as Fury should have been sent away too.
Joss Whedon revealed that Jeremy Renner injured himself during a stunt and caused production to halt for days. During the final battle scene where Hawkeye crashes through a window, Renner, who performed the stunt himself, ripped a muscle from his back to shoulder.
The planet of gods, where Loki is from, has a character with six fingers. It is widely known from Old Testament books of the Bible had fallen angels with six fingers, whom also thought they were a god.
Stark says "I can't do the equation without all the variables." This is very similar to a phrase said by Sherlock Holmes ("I cannot make bricks without clay"), another character played by Robert Downey, Jr.
Stan Lee: (at around 2h 10 mins) Creator of such Marvel comics as the X-Men, Spider-Man, the Incredible Hulk, the Fantastic Four, Iron Man, Thor, and many others, is the old man being interviewed at the end of the New York battle montage who says: "Superheroes in New York? Give me a break!" and then returns to a game of chess with a fellow senior citizen. He also appeared in a deleted scene: after witnessing a waitress flirt with Steve Rogers, Lee's character says, "Ask for her number, you moron!"
The trivia items below may give away important plot points.
It took Marvel three tries with the MPAA to grant the film a PG-13, instead of an R rating, because of Agent Coulson's death scene. Originally, Loki's staff was seen bursting through his chest. Instead, a gruesome sound effect was added after Loki appears behind him, and then a quick-cut to Thor's reaction.
(at around 2h) When the missile is released over Manhattan, the pilot calls detonation in two minutes and thirty seconds. The sequence between then, and the detonation, is two minutes and thirty seconds of film time.
In the final end credit scene, Captain America is the only one not eating. That is because Chris Evans got a buzz cut, and grew out his beard after The Avengers was done filming. He was called in later to do this extra scene, and refused to shave off his beard, due to having been filming Snowpiercer (2013) at the time, so they gave him a prosthetic jaw. He holds his hand over his face because the prosthetic made him look like he'd been attacked by a hive of angry bees. He also is unable to eat or talk with the prosthetic on. The wig he wears as Captain America is also quite clearly visible in certain shots of this scene.
The character, to whom the Other is talking, in the credits, is Thanos the Mad Titan, a major supervillain in the Marvel Universe. He is a cosmic mass murderer, who is literally in love with the personification of Death, which is why he is smiling at the phrase, "To court death".
Joss Whedon: [killing off a popular character] (at around 1h 28 mins) Agent Phil Coulson, a character who earned considerable popularity with fans through his appearances in almost all of the previous Marvel Studios films, is killed off in the middle of the film, giving the Avengers someone to avenge. In the commentary, Whedon says that it was not his decision to kill off Coulson in the film, and that Marvel Studios' Kevin Feige made the call. Whedon would later bring Coulson back in Agents of S.H.I.E.L.D. (2013).
(at around 2h 10 mins) When Pepper and Tony are in their apartment going over digital plans to rebuild Stark tower, the quinjet isn't the only visible clue to an Avenger's headquarters. The logo of each Avenger in the film can be seen on the digital canvas and Captain America's shield is selected to reveal his quarters in the blueprint.
Loki's staff has a glowing blue gem in the spear head that allows him to control the minds of others. This is a reference to the Mind Gem, one of the six Infinity Gems used by Thanos the Mad Titan, shown in the post-credits scene.
The decimation of Stark Tower during the final battle destroys the company logo, leaving only the illuminated "A" at the end of the film. This is a subtle nod (and sequel set-up) to the comics where the Avengers operate out of a giant building alternatively depicted as an "A" shaped building, or as a skyscraper with a giant "A" crowning the top.
Tom Hiddleston describes Loki in this film as having evolved since Thor (2011): "How pleasant an experience is it to disappear into a wormhole that was created by some super-nuclear explosion of his own making? I think by the time Loki shows up, he's seen a few things, and has bigger things in mind, than just his brother and Asgard."
(at around 1h 12 mins) A few seconds before Hawkeye's attack on S.H.I.E.L.D.'s Helicarrier, Bruce Banner finds the Tesseract's location on the computer. This explains why later he arrives in New York City during the invasion of the Chitauri, after the Hulk fell to the ground from the Helicarrier, during Hawkeye's attack.
According to Joss Whedon, it was his decision to include Thanos in a post-credits scene: "He, for me, is the most powerful and fascinating Marvel villain. He's the great-granddaddy of the badasses, and he's in love with Death, and I just think that's so cute. Somebody had to be in control, and had to be behind Loki's work, and I was like 'it's got to be Thanos'."
(at around 1h 9 mins) While Fury and the Avengers are arguing with each other on the Helicarrier, characters throw certain remarks that coincidentally foreshadow plot points in subsequent films: Steve asks Tony what he is without his armor, a topic deeply analyzed in Iron Man Three (2013); Fury aggressively chastised Thor about foreign species going to his planet to "blow stuff up", which comes into play in Thor: The Dark World (2013) with the invasion of Asgard by the Dark Elves. The most unassuming one (which is ironically translated into the biggest plot point in the whole cinematic universe) is when Bruce asks Natasha if Captain America is on threat watch, to which she replies "we all are". In Captain America: The Winter Soldier (2014), Steve (and by extension, Natasha herself) becomes a fugitive of S.H.I.E.L.D. after the murder of Nick Fury. Natasha also mentions that S.H.I.E.L.D. monitors potential threats, which plays heavily into this film as well.
In the post-credits scene, Pepper Potts shows Tony Stark a hologram of plans to rebuild the top of Stark Tower. In the hologram, a Quinjet is clearly visible in the middle of the structure, one among several hints in the film to the possible use of Stark Tower as future Headquarters of the Avengers (as occurred in the comic series).
Loki brings the Chitauri alien race to Earth to help him invade it. The Avengers are formed to prevent this from occurring. This is in keeping with the first issue of their self-titled comic book series, in which Loki is responsible for manipulating a chain of disasters that bring the Avengers together in the first place.
(at around 37 mins) Jasper Sitwell, outed as a HYDRA operative in Captain America: The Winter Soldier (2014), makes an appearance in this film. He is the Agent who first finds Loki in Germany, through the facial recognition they were running.
(at around 2h 10 mins) At the end of the film, when the news clip of the waitress appears on Nick Fury's computer screen it is listed as SHIELD File A113. "A113 is the room number of the animation classroom at CalArts. The A113 reference is a running gag in films made by Pixar and Disney, starting with Toy Story (1995), a film partially written by Joss Whedon, who wrote and directed this movie.
(at around 19 mins) When Black Widow calls off the "capture team", after first coming to terms with Bruce Banner, on helping S.H.I.E.L.D., a few of the team members are holding weapons with a blue glow coming from the barrels. Since they look nearly identical to the HYDRA weapons that Steve Rogers uncovers later, this hints at Fury's "Phase Two" project of weaponizing the Tesseract's energy.
(at around 37 mins) The classical music being played for the Stuttgart Museum, where they steal the eye-scan, so they can access the Iridium, is Franz Schubert's String Quartet No. 13 in A Minor, D. 804, Op. 29 ('Rosamunde').
Lieutenant Colonel James Rhodes was considered to have a cameo in the post-credits scene, where he is wearing his armor, only to find out he came too late for the battle, and sits down with the Avengers, but the scene was thrown away to where they just show the Avengers eating. Rhodes will now have a key role conflict in Avengers: Age of Ultron (2015). His role will be very important in the film, to where he could be one of the Avengers.
(at around 2h) When Tony Stark is fighting against the first Chitauri Leviathan, he asks J.A.R.V.I.S. if he knows Jonah's tale. According to the Bible, Jonah was God's prophet to Nineveh. Jonah ran from God's call, and when a big storm came upon the ship, in which he was traveling, he jumped over the side to save the passengers from God's displeasure. He was swallowed by a whale, and it delivered him to Nineveh after three days.
Thanos appears only briefly, but if you look at him, his chin is quite unique. The comparison to the Skrulls is very possible, that Thanos may be the progenitor of the Skrull Race. In the comics he is from the Titan moon of Saturn, whose fellow Titans have been Gods all across the Universe, creating races all over.
Foreshadowing. Just before the end, when Loki regains consciousness in Stark's tower and sees the The Avengers assembled over him, you can just briefly and barely see a trail of hair vertically across Thor's face, like a scar, going across his right eye. It could be a coincidence or perhaps a subtle clue of Thor losing his eye in Thor: Ragnarok (2017). It is also vaguely shaped like a lightning bolt, perhaps also alluding to Thor's acceptance and realization of his true power with the channeling and control of lighting.