According to Scott Watanabe, the movie is set in an alternate future where after the 1906 earthquake, San Francisco was rebuilt by Japanese immigrants using techniques that allow movement and flexibility in a seismic event. After the city was finished being rebuilt, it was renamed San Fransokyo due to it being a city with Japanese and American architecture combined.
In order to create the thousands of civilians living in San Fransokyo, the production team invented a program called the "Denizen Factory," which allowed them to build a whole series of background characters that each have a distinct design.
In the science expo, whilst Hiro is demonstrating the microbots, there are two brief shots showing Alistair Krei assessing another competitor's project. The competitor is wearing something very similar to the Brain-Wave Analyzer created by Dr. Emmett Brown in the film Back to the Future (1985).
The first animated Marvel film to be released theatrically via Walt Disney Animation Studios. However, the film does not share the same universe as the live-action Marvel Cinematic Universe, nor is it branded as a Marvel property from Marvel Studios.
The Portal testing lab was meant to be located deep in the catacombs of Alcatraz, but was changed to an alternate version of Angel Island called Akuma Island. Akuma means "demon" or "devil" in Japanese.
Two important characters from the Big Hero 6 comic, Silver Samurai and Sunfire, did not make it to the film. This is because 20th Century Fox owns both characters, because of their affiliation with the X-Men. However, Tadashi's cap has the SF emblem, which is written in the same font as in the Sunfire comic.
Don Hall chose San Francisco as the city to be blended with Tokyo because Los Angeles isn't a massive city, and New York is too common an epicenter for the Marvel comic world. San Francisco also has many distinctive features that aren't present in Los Angeles or New York.
Hiro mentions that one of Callaghan's inventions is the Callaghan-Catmull Spline. The Catmull-Rom Spline is a mathematical construct used in computer modeling and animation co-invented by Pixar president Ed Catmull.
Fred mentions that he likes to make movies about himself in a rubber suit stomping on boxes. This is a reference to his original power: the ability to transform into a giant monster that can stomp down houses.
According to Sang-Jin Kim, When creating GoGo, Kim and his team originally thought of South Korean actress Doona Bae and then incorporated independent and athletic traits after Korean short track skaters.
Gogo is Disney's first Korean character. Lead character designer Shiyoon Kim drew upon his experience with 'tough' sister stereotypes while mixing it in with the bike messenger/trick culture of San Francisco.
In I, Robot (2004), James Cromwell starred as Dr. Alfred Lanning, creator of the robot, Sonny, played by Alan Tudyk. In this film, Cromwell plays Dr. Robert Callaghan, the rival of Alistair Krei, also played by Tudyk.
Sang-Jin Kim, the first Korean to become the top animator at Walt Disney Studios and character design supervisor for Big Hero 6, revealed that the lead characters, although they were later given Japanese names, were originally envisioned as Koreans.
In the opening bot battle, Hiro goes up against Yama, a very large man controlling a battle-bot. When Yama turns and shows his back, the Japanese character for "mountain" ("yama") is embroidered on his jacket, as a joke about his large, 'mountain-like' size.
Akuma Island was originally going to be an abandoned military base where Yokai was going to steal a nuclear submarine to power the Portal. At one point a monster called the Entity was going to emerge from the portal and lay waste to San Fransokyo. But eventually the production decided that the Portal's purpose is for teleportation only.
In the back of Fred's room is a display case with two mannequins wearing the costumes of two lesser Marvel comics super villains. The blue mannequin on the left is of the Sub-Mariner villain "Orka", and the chicken themed one on the right is that of the voodoo priest villain known as "Black Talon."
During the first flyover shot of the interior of the building where the SFTT showcase is being held, in the left hand corner characters resembling Steve Jobs and John Lasseter can be seen talking to a blonde woman with a pony tail. According to the Blu-ray's special features, the guy that looks like Steve Jobs is actually Ed Catmull, co-founder of Pixar and president of Walt Disney and Pixar Animation Studios. To his left is John Lasseter, co-founder of Pixar and executive producer of Big Hero 6, and on the right is the president of Disney Animation Studios Andrew Millstein.
When Hiro first meets everyone at the college, Honey says her ball of carbide weighs 400 pounds. In reality, a ball of carbide measuring 36" in diameter (judging size from the film) would weigh over 14,000 pounds.
There are multiple references to the short film Feast (2014), which is a special feature in the video, throughout the movie. Two "Adopt a dog today!" posters are seen in the overhead view of a street market at 30min:46sec, and at 44min:36sec, a graffiti version of the title Feast is shown on the alley wall as the Greek letter "phi" and "st" (pronounced "feast") with 4 paw prints and the parsley garnish featured predominantly in the short film.
Although the writer/creator think tank Man-Of-Action is credited for creating the team in the film (Duncan Rouleau & Steven T. Seagle specifically) the characters of Fred and Wasabi are co-creation of legendary X-Men writer Chris Claremont & artist David Nakayama from their Big Hero 6 mini-series.
Hiro's nervous tic when he catches his reflection in the side of a building was actually derived from Ryan Potter's own body language in the recording booth. Potter said he was amazed when he saw this incorporated into the animation.
When the six heroes enter Fred's big room for the first time, we can see on the left of the door a statue of Torpedo (the statue in the middle). Torpedo is an ex Marvel villain (mainly against Daredevil) and then hero (mainly alongside Rom Spaceknight). He's got a blue suit and turbines on his ankles and his wrists. His face is never shown in close-up. The last Torpedo, Brock Jones, died in battle against the Dire Wraiths, evil aliens enemies with Rom Spaceknight.
The film might also draw inspiration from Big Hero 6's mini-series, where Wasabi and Fred first appeared, replacing Silver Samurai and others. Since Disney took Wasabi and Fred as characters of the film, it's likely that Disney also took inspiration from the series' setting: America. This can explain the creation of San Fransokyo.
This film became the thirteenth highest grossing Disney film, and it is also one of the 4 highest grossing Disney films that are not made by Pixar Animation Studios, The other 3 are: The Lion King (1994), Frozen (2013), and Zootopia (2016).
As Hiro stands on the steps talking with Aunt Cass about wings, right after shoving Baymax upstairs, there are pictures hanging up behind him on the wall. Over his left shoulder you can see Stitch from Lilo & Stitch (2002).
Big Hero 6 (2014) is only the second fully CGI film to be based on a comic strip. The first one was the Dreamworks Animation film Over the Hedge (2006), released eight years prior, and the third would be the 20th Century Fox animated film The Peanuts Movie (2015), released a year later.
The name of the character Alistair Krei is probably based on Seymour Cray, who from the early 60's to the mid 90's, designed many of the world's most powerful supercomputers, and is considered the "father of supercomputing".
This is the second robot-themed animation that features a brief sequence of Survivor's "Eye of the Tiger" that has nothing to do with its original use - Rocky III (1982). The first movie to do so was Robots (2005).
Two distinctly shaped shield emblems can be seen hanging on the wall during the post-credit scene. These shields are modeled after the faction insignias of the Alliance and the Horde from the MMO game World of Warcraft.
In Fred's mansion, a portrait of Stan Lee, Chairman Emeritus of Marvel Comics, can be seen as Fred's dad (and in a post-credits scene). As in all Marvel-related movies, part of the contract was to feature him in some way.
Big Hero 6 (2014) contains a large number of hidden "Easter eggs" from other Disney animated features: Hiro's cat, Mochi, is wearing a Stitch costume from Lilo & Stitch (2002) in the picture hanging in the stairway of his house. Hiro has a figure of Wreck-It Ralph (2012) on his computer monitor. The arcade game Sugar Rush is seen in an arcade. At the police station, there is a wanted poster over the shoulder of the police officer that not only has Hans from Frozen (2013), but also one of the misdrawn pictures of Flynn Ryder from Tangled (2010). Stan Lee also make his obligatory Marvel cameo, not only in the family portrait, but also in the after-credits scene. Bolt (2008) can be seen in a picture (as noted above). Also the statue destroyed by Baymax's rocket fist is a statue of Prince Hans from Frozen (2013).
Originally there were going to be more villains in the movie besides Yokai. One was a group called the Fujitas. According to the Big Hero 6 art book, they were going to be a trio of deadly Geisha women each possessing a different weapon with movements inspired by the movements of snakes or koi fish. The second villain was going to be a Japanese TV Talk Show Host named Mr. Sparkles who was a child-like man devoted to world conquest. The last was a group of jet pack flying pilots called the Banzai Bombers.
In Hiro's bot fight against Yama, Megabot (Hiro's robot) is seen removing the arm of Yama's robot, using it to cause Yama's bot to attack itself. Then Megabot is seen punching Yama's bot rapidly in the head. This resembles the scenes in The Incredibles (2004), in which Syndrome's robot is destroyed by its own arm, and the scene where Dash punches a villain in the face rapidly.
In the final scene of the movie, when Hiro puts the robotic hand on his shelf, there is a large yellow book on top of the shelf with the name "McMaster-Carr" on the spine. Mcmaster-Carr is a supply house with a catalog of over 550,000 electrical, hardware, mechanical and other products. The annual catalog is yellow, and the 2014 edition is nearly 4,000 pages long.
In the first scene in the college lab, each one of the main characters are working on something that helps them in the battles in this movie. Gogo is making a speedy bike which later is added to her suit to make her faster, Wasabi is working on lasers which get turned into his arm blades, Honey is working on chemical orbs which later become her main weapon, and Fred shows his sign spinning which aides him in the final battle.
This is the second time James Cromwell has played a character who invented the 3 laws of robotics, previously in I, Robot (2004). In fact, the plots of the two films are quite similar. An army of seemingly benign robots are hijacked by an unknown 3rd party. A 'big brother' of the hero is killed early in the movie, leaving him a robot companion. The unknown 3rd party then uses their robot army in order to gain power and take over the city. The hero and his robot companion slowly discover that this 3rd party is not who they originally suspected and is in fact someone they met early in the story but thought nothing of. Some of the character roles are switched around but the plots are very similar.
Early on in the film, when Hiro is struggling for ideas for the showcase, Tadashi tells him to "look for a new angle." During the film's climax, when it appears that the gang is about to be defeated by the Microbots, Hiro tells them to "look for a new angle."
One of the life-sized models in Fred's room is the Sleepwalker. Sleepwalker is a Marvel Comic that ran for 33 issues from 1991-1994. The Mindscape from which Sleepwalker hails strongly resembles the ethereal plane on the other side of the portal where Abigail Callaghan is trapped.