Originally, the idea was that Jean Grey was temporarily rendered blind after her violent reunion with Cyclops. This was initially filmed as such, but ditched during production. When Wolverine shuts a dam door, saving the X-Men from a wall of water, Jean Grey is the only character not looking at him.
On The Tonight Show with Jay Leno (1992), Hugh Jackman related a story about something that happened during the filming of the Weapon X flashback scene: while he was filming the corridor run (in which he is nude and backlit), he turned the corner and saw the female cast members, and also James Marsden's mother, waiting for him, hooting and waving dollar bills.
During filming, Hugh Jackman's sister visited the set. As a joke, she was made-up in Jackman's full Wolverine costume and make-up, and walked around the set. Apparently, she was very convincing as Jackman. Bryan Singer was not aware that it was not Jackman in the Wolverine costume, and commented of her work during shooting, that: "Hugh is acting very strangely today."
Professor Xavier's wheelchair from the first X-Men (2000) movie was bought by a lawyer who also worked for the same law firm as Sir Patrick Stewart's attorney. When production began, the studio realized they had no chair anymore, so the lawyer rented it back to the studio - as Stewart said in an interview - "for a significant sum."
(at around 8 mins) When Jean is hearing people's thoughts in the Science Museum, one of them is "To the shelter!" This line was said by one of the Secret Service during Nightcrawler's attack on the Oval Office in the previous scene, thus adding and alluding to Jean's growing psychic abilities. Other lines Jean hears are "No!" shouted by Wolverine when he later is separated from General Stryker by Iceman's wall of ice and "They're gonna kill him.", which is what Rogue later says to Iceman and Pyro in the tunnel pleading for them to go back and help Wolverine.
(at around 26 mins) The German phrases that Nightcrawler shouts to Storm and Jean in the Boston church are "Gehen Sie raus! Ich bin ein Büttel des Teufels! Ich bin die Ausgeburt des Bösen!" They translate to "Get out! I am a minion of the devil! I am the spawn of evil!"
Initially, during the "Dark Cerebro" scene, where it is attempting to kill all mutants, Bryan Singer had planned to show not only Cerebro's effects on the mutants in the Alkali Base, but mutants all over the world. During this scene, Hank McCoy, a.k.a. Beast (Steve Bacic), as seen earlier on the television during the bar scene, was to be shown in agony, transforming into his furry form, and fan-favorite Gambit was to be shown at a card game having his energy powers flare up. This scene was actually shot, using one of Hugh Jackman's stunt men, James Bamford as a stand-in for the role, shot from behind to remain ambiguous. For whatever reason, Singer decided to cut this sequence altogether and it remains unseen.
Bryan Singer credits the X-Men graphic novel "God Loves, Man Kills" (released in 1982) as an influence for the script. As in the film, the novel concerns William Stryker (a religious leader instead of a military one) building a replica of Cerebro and kidnapping Professor Xavier so he can use it to kill all mutants. The X-Men are forced to ally themselves with Magneto to stop him.
The set for Stryker's underground lair was built in an old Sears warehouse, and was the largest set in North America. It involved over sixty miles of cable, and was so large, that cast and crew members used bicycles, to get them to and from the bathroom as quickly as possible. Even then, the production only used about half the space in the warehouse.
(at around 1h 9 mins) Magneto's line "When will these people learn how to fly?" is a reference to the fact that some of the characters (Jean Grey and also Rogue, who gets the ability from permanently absorbing Ms. Marvel's powers in the comics) have the ability to fly in the comics, but haven't yet in the films. The only characters with the power of flight in the comics that have shown this ability in the movies are Magneto and Storm (although Storm was manipulating wind currents to levitate herself, and Magneto was only able to levitate by standing on metal, presumably he wears shoes with metal sole-plates to do this on other occasions). Though it can also be seen as a reference of them to having difficulties to either fly or at least land the jet properly throughout the movie franchise.
Alan Cumming (Nightcrawler) left the franchise after one movie, because the crew believed it wasn't worth going through the long preparation. This also includes the fact that Cumming did not enjoy putting on the heavy make-up, because his appearance was minimal. So, it was written in the video game series that Nightcrawler decided to leave, because he no longer wanted to live the violent lifestyle that X-Men have to endure.
Several sets for the film were not used. Some of these sets included the Danger Room, and several areas in Stryker's underground bunker. One room in Stryker's underground base was going to be the setting of a Nightcrawler vs. Toad fight.
The White House oval office is an exact re-creation, but the corridors in the opening chase between Nightcrawler and the Secret Service, were wider than the actual walls, to allow more room for fighting.
The final scene in Xavier's mansion with Cyclops, Wolverine, and Professor X, was shot at Shepperton Studios in London, simply because Hugh Jackman was shooting Van Helsing (2004) at the time, and the producers released him for only one day to do the final shooting of this movie. The reason Wolverine's hair looks higher than usual in this scene, is because Jackman had long hair for Van Helsing, and had to wear the Wolverine wig over a lot of hair.
(at around 45 mins) In the bar, the television is showing a debate on the mutant situation. One of the panelists is "Dr. Hank McCoy", which is the real name of the blue-furred behemoth X-Man, Beast, who then is played by Kelsey Grammer in X-Men: The Last Stand (2006) and X-Men: Days of Future Past (2014). The other, not seen, but called "Dr. Shaw", is presumably Dr. Sebastian Shaw, the leader of the Hellfire Club in the comics, and the main bad guy of X: First Class (2011).
(at around 1h 45 mins) Health and safety restrictions meant that helicopter blades were not allowed to be moving when Rebecca Romijn and Sir Ian McKellen were sitting inside the helicopter. The moving blades had to be added in digitally afterwards.
Guy Hendrix Dyas and sculptor James Jones collaborated on designing a Sentinel (in the comics, the Sentinels were a set of mutant-fighting robots constructed by anti-mutant government officials). Their final design was a complex hollow robot that could compress itself into a discus. Animating the Sentinel would have cost about seven million dollars, so the Sentinel was never used in the film.
(at around 1h 30 mins) When Wolverine visits the adamantium processing chamber of Stryker's Alkali Base, there is a wall covered with x-rays detailing the adamantium bonding process. On the far right is an x-ray of what appears to be a left wing. The DVD acknowledges this as a hint to a winged character named Angel, who was introduced in the next movie X-Men: The Last Stand (2006). In the comic books, Angel's wings are replaced with metal ones, and he becomes Archangel.
The mansion used for the school also appears as Lex Luthor's mansion in Smallville (2001), another comic book based epic. Before that it was the title character's mansion in the light-hearted comedy Billy Madison (1995).
(at around 24 mins) On Yuriko's computer, the following files of various comics characters, both famous and obscure, are listed: Guthrie (2) (Paige (Husk), and Samuel (Cannonball)); Harada, Keniucho (Silver Samurai); Kane, Garrison (Weapon X); LeBeau, Remy (Gambit); Lehnsherr, Erik (Magneto); Maddicks, Artie; Madrox, Jamie (Multiple Man); Xi'an Coy Mahn (Karma); Maximoff (2) (Wanda (Scarlet Witch), and Pietro (Quicksilver)); McTaggart, Kevin (Proteus); Moonstar, Danielle (Moonstar); Munroe, Ororo (Storm); McCoy, Hank (Beast); Callasantos, Maria (Feral); Cassidy (2) (Sean (Banshee), and Tom (Black Tom)); Cheney, Lila; Creed, Victor (Sabretooth); DaCosta, Roberto (Sunspot); Dane, Lorna (Polaris); Drake, Bobby (Iceman); Dukes, Fred (Blob); Espinosa, Angelo (Skin); and Gibney, Kyle (Wild Child). On another screen, there were a series of folders on the computer's desktop. These folders listed some well-known individuals or places from the X-Men universe, including: Omega Red (Russian mutant super soldier), Muir Island (Scottish mutant research facility), Project Wideawake (Codename for the Sentinel project), Franklin Richards (son of Fantastic Four's Reed Richards and Susan Storm; born a mutant), and Cerebro (mutant tracking device created by Professor Xavier and Magneto). Closer inspection reveals that Stryker is keeping files on Pyro, Sabra, Dr. Cecilia Reyes, Synch, Penance, Nightcrawler, Mystique, his own Lady Deathstrike, Copycat, Deadpool, Cyclops, Dazzler, the Von Struckers, Jamie Braddock, David North, Sunfire, Boom Boom, Mimic, Dr. Nathaniel Essex (Mr. Sinister), Toad, Wolfsbane, Strong Guy, Kitty Pryde, Sauron, Forge. Curiously, there seem to be no files for Jean Grey or Wolverine, among others. There are also files on Alpha, Beta, and Gamma Flights, Weapon X, Project Wide Awake, Department H, the Brotherhood, Graymalkin, Zero Tolerance, Massachussets Academy, Blackbird, the Danger Room, Legacy, Morlocks, Xavier's School, Omega Red, Cerebro, the Salem Centre, Franklin Richards, Kevin McTaggart, and Bolivar Trask.
In the film, William Stryker is an Army Colonel, who perceives mutants as a threat. In the comics, he is a Christian fundamentalist televangelist, who uses religion and his sacred belief of all mutants being satanic, to rally anti-mutant bigotry. He even set up his own hate group in the comics called "The Purifiers" to eliminate mutants in a holy crusade. This change was likely meant to avoid religious controversy, because of the religious intolerance and terrorism themes from the original comics.
Alan Cumming was Bryan Singer's first choice for the role of Nightcrawler. However, during initial casting, he was unavailable. The project labored in development long enough that by the time the film was ready to shoot, Cumming was able to come onboard. Ethan Embry was rumored to have won the role, before Cumming was available.
Character-development-heavy scenes of Cyclops and Professor X being brainwashed by Stryker were shot, but 20th Century Fox cut them out, because of time length and story complications. David Hayter was disappointed, feeling that James Marsden deserved more screentime.
Another huge set was the turbine hall of an old dam, which housed a museum. Unfortunately, the museum was painted in bright, lurid colors, so the Production Design team had to dress it up to make it look old and dank (something which horrified the museum administration, until they realized that it was just temporary).
(at around 3 mins) The music played in the opening scene when Nightcrawler attacks the White House is "Dies Irae" from Wolfgang Amadeus Mozart's Requeim. (Alan Cumming, who plays Nightcrawler, shares the same birthday as Mozart.)
Xavier's School for the Gifted is located on "Graymalkin Lane, Salem Center". "Graymalkin" was the name of the witches' cat in William Shakespeare's Macbeth (Act I, Scene I: "I come, Graymalkin!"), and Salem Village (now Danvers) in Massachusetts was the location of the infamous witch trials in 1692.
The character Rogue, whose surname has never been revealed since her introduction in the comics in 1981, was given a surname for this film, Marie D'Ancanto. Comic Writer Chris Claremont, Rogue's Creator, has used this name since the movie's release in the "X-Treme X-Men" comic, but for a different character.
The Danger Room, the area where the X-Men train and hone their powers, was going to be included in this film. Bryan Singer had wanted it to appear in the first film, but due to budget cuts, the idea had to be scrapped. It was then worked into the story for this film, to take place when Wolverine is left to watch after the students in the mansion. He decides to do a workout in the Danger Room, which was going to segue into the scene of him lying down and having a vision of Stryker and his Weapon X procedure. The Danger Room was going to be a cylindrical-shaped room, with different sections of the floor raising and lowering at dangerous speeds, as well as holographic projectiles, et cetera. The earliest teaser trailer for the film gave a sneak peak at how the Danger Room was going to look, but shortly after this teaser was released, 20th Century Fox cut Singer's budget down from one hundred twenty-five million dollars, to one hundred ten million dollars, forcing Singer to once again cut the Danger Room from the film. There is still a small reference to the Danger Room remaining in the film: when Stryker first enters the X-Mansion sub-basement, directly opposite from the elevator is a door with a small label on it, which, according to Singer's DVD commentary track, identifies the door as the entrance to the Danger Room.
Kurt Wagner is also the name of the composer of tunes like "Life's little tragedy" and "The daily growl". The dialogue of the movie's character Kurt Wagner contains several references to the composer's songs lyrics.
Two of the voice actors from X-Men: Evolution (2000) appear in the movie. David Kaye, who voiced Professor X, appeared as a television announcer. Chiara Zanni, who voiced Jubilee, a.k.a. Jubilation Lee appeared as a White House tour guide.
(at around 24 mins) When Mystique is hacking into the computer you can shortly see a file under the name of "Maximoff (2)". This is referring to the Maximoff twins Pietro a.k.a. Quicksilver, and Wanda, a.k.a. Scarlet Witch. We see both twins in Avengers: Age of Ultron (2015). Peter Maximoff, a.k.a. Quicksilver, makes his solo appearances in X-Men: Days of Future Past (2014) and X-Men: Apocalypse (2016).
Chuck Austen, who has written extensively for the character of Nightcrawler, revealed on the DVD that he was asked if there was anything he knew about the character that nobody else did. He suggested that, just like the character has two fingers on each hand and two toes on each foot, he also had two sets of genitals.
David Hayter and Zak Penn wrote separate scripts for the sequel and the best elements were combined to make the screenplay (this is a relatively common practice for summer blockbusters). Michael Dougherty and Dan Harris were then brought in to hone the final script. Two of their major contributions were the removal of a scene set in the Danger Room (later reinstated for X-Men: The Last Stand (2006)) and the presence of the Sentinels (which would later serve as the menace in X-Men: Days of Future Past (2014)).
(at around 52 mins) When Wolverine is in the kitchen in Bobby Drake's parents' house, and he is surprised by the cat, he lets it lick his claws, seemingly a very cute moment. But if you listen closely, when he hears someone come in and retracts his claws, you hear the sound effect of Wolverine's claws extending (if you listen closely, you can tell the difference, as the retracting sound is the same as the extending sound, but played in reverse), and then the cat crying out. This was an unintentional moment of comedy, which was going to be cut, but the last minute decision was made to leave it in.
There was an extended scene that doesn't appear in the final film, nor as a deleted scene on the DVD that features Cyclops' fight with Yuriko (Lady Deathstrike), where he picks up and fights with the two prison guards' plastic nightsticks.
The sunglasses worn by Cyclops are Oakley Pennys, although they look very similar to the glasses he wore in the original X-Men (2000) they are in fact a different model (with Oakley Juliets appearing in the first film), both were modified with blinders around the lens. Oakley were also responsible for manufacturing the visor which Cyclops wears and in some shots Oakleys logo (a horizontally stretched "O") can be seen on the parts of the visor that cover Cyclops' ears.
(at around 24 mins) When Mystique reviews the information on the security guards at the facility housing Magneto, the following names are displayed, referencing crew members of the film: DeSanto, T. (Tom DeSanto, Executive Producer); Dougherty, M. (Michael Dougherty, Screenwriter); Donner, L. (Lauren Shuler Donner, Producer); Young, R.D. (possibly Rob Young, Production Sound Mixer); Harris, D. (Dan Harris, Screenwriter) C. L. G. - Classified; R. G. M. - Classified, and; Singer, B. (Bryan Singer, Director). Bryan is the only one who gets his own photo. The others, including Mrs. Donner, are given stock male guard photos.
Though Cinematographer Newton Thomas Sigel shot the first X-Men film in anamorphic format, he opted to shoot this one in Super 35. Sigel felt the recent improvements in film stocks and optics increased the advantages of using spherical lenses, even if the blow-up to anamorphic must be accomplished optically instead of digitally: "Every anamorphic lens is simply a spherical lens with an anamorphizer on it. They'll never be as good as the spherical lenses that they emulate."
This is the second time that Bryan Singer has done a cameo with Sir Patrick Stewart (Singer plays one of the guards at Magneto's plastic prison facility). Singer also appeared for nineteen frames in Star Trek: Nemesis (2002).
The international cast includes Magneto (English), Professor Xavier (English), Wolverine (Australian), Nightcrawler (Scottish), Rogue (New Zealander), Jean Grey (Dutch), Iceman (Canadian), Stryker (Scottish), the rest are from the U.S., including Lady Deathstrike, who is Hawaiian.
(at around 51 mins) When Rogue is shirtless in Bobby's bedroom, Anna Paquin was topless, but only her bare shoulders were seen. Anna Paquin wouldn't go fully nude on-screen, until the television series True Blood (2008), which she starred as Sookie Stackhouse.
The film's main antagonist, William Stryker, is an amalgam of various X-Men villains: Reverend William Stryker, an anti-Mutant bigot; Professor Andre Thorton, the malevolent mastermind of the Weapon X program; and Henry Peter Gyrich (whose name was used for a minor character in X-Men (2000)), a ruthless government official who dedicates his life and resources to destroying the Mutant populace. Both of the latter characters being identified by their eye glasses, similar to Stryker in the film.
Nightcrawler's appearance in the opening, is a reference to the comics, and X-Men: Evolution (2000), where he uses a hologram watch to appear human. In the film, it is never explained how Nightcrawler was disguised, however, it could be similar to the serum that Hank McCoy pioneered in X-Men: Days of Future Past (2014).
(at around 1h 50 mins) Rogue's controlling and trying to fly the Jet, alludes to the comic book storyline, where she absorbs all of Ms. Marvel's powers. In the comics, Rogue doesn't let go of Ms. Marvel, and in the movie, she doesn't let go of the Jet's handles.
Kurt Wagner's x-rays are all given the same id: C13957. They are all dated May 22/84, and taken by Dr. D.Mintz (69) at the offices of "Drs. Green, Chetwynd, Gough, Switzer, Siu, Fulton, Bentley, Murray. Radiologists. Vancouver, BC."
After production was completed on the film. Rebecca Romijn starred in another Marvel comic book film The Punisher (2004). Hugh Jackman was offered to play Frank Castle, a.k.a. The Punisher, but turned it down to do Van Helsing (2004) and the part of Frank Castle, a.k.a. The Punisher was given to Thomas Jane.
(at around 35 mins) While Professor X and Cyclops are visiting Magneto at his plastic prison and both of them are abducted, one of the students is watching a nature documentary about mother rats and the danger of leaving it helpless babies alone. Immediately afterwards, Stryker's men attack the school and kidnap the children.
When Mystique is looking at Stryker's computer files, there is a list of mutant names, including a few we will see in later films. However, there is one name that grabs your attention: Kevin MacTaggert (a.k.a.: Proteus). This is the mutant son of Moira MacTaggert, played by Rose Byrne in X: First Class (2011) and X-Men: Apocalypse (2016), as Professor X's (James McAvoy) love interest. He is not the son of Professor X, as he hadn't seen Moira again for twenty years. He has a human father (villain), Joe MacTaggert.
In William Stryker's backstory: Stryker had sent his mutant son Jason to Professor Xavier's School for the Gifted, so Jason could be cured of his disease, and was angered when Professor Xavier told him that Jason's mutation is not a disease, and Stryker accused Professor Xavier of lying. But, Jason used his mutant powers to project images and visions in the mind of his mother, which drove Stryker's wife to commit suicide, and Stryker made it his personal mission to rid the world of all mutants, and Stryker schemed to use Jason to project images into Professor Xavier's mind and to manipulate him to use Cerebro to commit genocide upon the mutants.
Originally, Bryan Singer planned to use a visual-effects heavy scene involving the X-Men's training facility, the Danger Room. But budget cuts and timing nixed the scene, even though Ultimate X-Men artist Adam Kubert had already storyboarded the scene. A Danger Room scene did appear in X-Men: The Last Stand (2006) and X-Men: Apocalypse (2016).
Like earlier Marvel comic book films The Punisher (1989) and Blade II (2002), this film sees The X-Men forced to make an uneasy temporary alliance with their enemy The Brotherhood against a common enemy Major William Stryker, who is bent on committing genocide upon the mutant race.
Aaron Stanford (John Allerdyce/Pyro) and Shawn Ashmore (Bobby Drake/Ice Man) have both worked with actress Amanda Schull: Aaron and Amanda appeared together in the TV show '12 Monkeys', playing James Cole and Dr. Cassandra Railly respectively, while Shawn and Amanda appeared in the movie 'Devil's Gate', playing Conrad 'Colt' Salter and FBI Special Agent Daria Francis respectively.
The trivia items below may give away important plot points.
Although this idea did not carry into the films, in the comics, Nightcrawler was the son of Mystique and Azazel, a member of the Hellfire Club, who was introduced in X: First Class (2011). He gained his mother's blue skin, and his father's slightly demonic appearance and teleportation abilities.
Throughout the film there are homages to Jean Grey's alter ego the Phoenix: - When Jean and Storm are in the church looking for Nightcrawler, Jean is wearing a jacket with a Phoenix on the back. - As Jean Grey uses her powers, a fiery aura appears in her eyes - At the end of the film, as the camera is gliding over the water, a large, bird shaped shadow can be seen. This is most likely a reference to Jean Grey being resurrected as the Phoenix.
According to Bryan Singer, he conceived the idea of Jean Grey's death midway through production. During the filming of the museum scene, he privately met with Famke Janssen to discuss the concept of Jean dying at the end of this film, with the allusion to her return as Phoenix (as in the comic book mythology) in X-Men: The Last Stand (2006). Janssen enthusiastically agreed.
An early draft of the script had Magneto saving Professor X from Dark Cerebro and escaping with the other X-Men, similar to what happened in the comic graphic novel that the film is based on. According to Bryan Singer, this was changed late in production, not only to remain true to Magneto's ruthless character, but also to give the other characters, namely Nightcrawler and Storm, something more to do in the film's climax.
The set from the bathroom scene where Mystique incapacitates the prison guard, and injects him with a foreign substance is actually an unused set from X-Men (2000). The scene in question (written and storyboarded, but not shot) involved Cyclops manifesting his powers as a teenager, destroying a high school bathroom. This scene has since been used in X-Men: Apocalypse (2016).
In the final classroom scene, Professor Xavier talks about a book called "The Once and Future King" by T.H. White. Magneto was reading the same book (a retelling of the King Arthur legend) in prison before Stryker's interrogation, and is meant to point at Magneto being a once and future leader of mutants.
According to Bryan Singer's commentary, he removed a couple of seconds of footage after Wolverine stabs a soldier in the kitchen during the raid for ratings purposes. But the extended sequence can be seen as deleted footage in the Supplemental Features disc. The extended sequence was also featured in the theatrical version in other countries (for example, Brazil).
at around 1h 2 mins) Rogue's powers not only take human and mutant abilities, but also their memories and feelings. This is evident when Rogue is absorbing and using Pyro's power to stop the fires, she has a menacing face just like Pyro had when destroying the police cars.
at around 1h 2 mins) When Pyro attacks some police cars, the original idea was that Storm would douse the flames by bringing on the rain. However, this proved too costly, so the idea was hatched to use Rogue instead. This was a fortuitous decision, as it enabled the writers to create a character-defining scene where Rogue actually takes ownership of her own powers.
at around 55 mins) All the breaking glass in Magneto's escape from his glass prison was computer generated. This makes for a much safer working environment and also means that repeated takes can be filmed with minimal effort.
The first X-Men film which Magneto works with the X-Men to fight a common enemy. In X-Men: Days of Future Past (2014), Magneto aids Professor Xavier and the X-Men against the Sentinels in the post-apocalyptic 2023, and Magneto and Professor X both send Wolverine back in time to 1973.
Professor Xavier's abduction and Stryker's military force invading Xavier's school in the middle of the night which they capture seven children was foreshadowed in X-Men (2000) in Magneto's dialogue in the final scene, which Magento says to Professor Xavier "Does it ever wake you in the middle of the night? The feeling that one day they will pass that foolish law or one just like it, and come for you? and your children?"