Josh Schwartz wrote an early version of the screenplay, but once Bryan Singer became attached, Schwartz's script was ditched as Singer wanted to take the story in a different direction. Jamie Moss was subsequently hired to write a new draft.
To prepare for his role as Charles Xavier, James McAvoy shaved his head... and learned that the filmmakers wanted Xavier to have a full head of hair in the prequel. Throughout the first month of filming McAvoy had to wear hair extensions. He finally shaved his head for X-Men: Apocalypse (2016).
Although they barely interact during this movie (and in fact are antagonists through most of it), according to Marvel Comics canon Azazel and Mystique eventually have a child together; Kurt Wagner a.k.a. Nightcrawler. He appears in X2 (2003), played by Alan Cumming and again in X-Men: Apocalypse (2016), played by Kodi Smit-McPhee
During the Cerebro sequence one of the mutants seen is Cyclops as a young boy, playing with a glove and baseball, noticeable by his sunglasses. Another is 'Storm' who is noticeable by her characteristic long, white hair.
To prepare for his role as Erik Lensherr, Michael Fassbender studied Sir Ian McKellen's performance as Lensherr in the previous X-Films, but also looked through the comics as he decided to make his own version of Magneto: "You want to respect what someone else has done, especially because the fan base really liked what Ian has done with it. But while I could have gone and studied him as a young man and brought that to the performance, I don't think Matthew is very interested in that. So I'm just going my own way and working with whatever is in the comic books and the script."
Bryan Singer, who directed X-Men (2000) and X2 (2003), was approached to direct this film in October 2009, but in March 2010 declined due to his commitment to Jack the Giant Slayer (2013) and was replaced with Matthew Vaughn in May 2010. Singer however stayed on as producer.
Caleb Landry Jones auditioned for the film without knowing what X-Men character he was up for, saying he auditioned because it was the film that fit his biotype: "I've got red hair and freckles, I'm not gonna be Batman, Robin or Spider-Man."
In addition to his comic book persona, the character of Sebastian Shaw (Kevin Bacon) takes on qualities of Nazi scientist Josef Mengele. Mengle is noted for his eugenic experimentation and torture often with children, to whom he would offer candy to gain their trust.
Morgan Lily, who played the 9-year-old Mystique, wore a slip-on bodysuit and facial appliances which only took one hour and a half to apply, as subjecting a child actor to the extensive make-up was impractical.
During the American/Soviet standoff, the Soviet captain refers to the man behind him as "zampolit", which is inaccurately (but not completely incorrectly) translated in the subtitles as "comrade." A Zampolit is a political officer responsible for political education and enforcing Party loyalty (in this case, on a ship), and is capable of countermanding the orders of the officer he's attached to, if they conflict with Party doctrine. The fact that it's actually the Zampolit that fires the missile to destroy the freighter is a sly bit of irony on the part of the film producers.
The uniforms the X-Men wear are colored blue and yellow, in homage to the original blue/yellow suits the X-Men wore in the comics from 1963 (their debut) until (original artist and co-creator) Jack Kirby's departure from the book. After several costume changes throughout the years, the costumes used in X-Men (2000) inspired new black leather uniforms seen in the Grant Morrison written 2001 New X-Men comic).
The set for Xavier's mansion was also used in a TV series called Hex (2004), which also starred Michael Fassbender, who played a character named "Azazeal" which is much like the teleporting mutant named "Azazel".
Matthew Vaughn instructed the cast to do away with all accents in their performances. James McAvoy had planned to copy Patrick Stewart's voice (since McAvoy was going to play a younger version of Stewart's Xavier), but Vaughn quashed it; Vaughn also told Rose Byrne that Moira MacTaggert would not have her trademark Scottish accent in the film (to the Scottish McAvoy's mild disappointment).
One line was changed in the famous John F. Kennedy speech of Oct 22, 1962. The changed line was voiced by Jim Meskimen. The original line was "It shall be the policy of this nation, to regard any nuclear missile, launched from Cuba against any nation in the western hemisphere, as an attack by the Soviet Union on the United States." In the film the line goes: "..to regard any nuclear missile crossing the embargo line that now surrounds Cuba, as an attack by the Soviet Union..."
The film was originally to be a prequel about Magneto. Screenwriter Sheldon Turner wrote a treatment which he described as "X-Men (2000) meets The Pianist (2002)": the story focused on Magneto's early years as a prisoner of war in a Nazi concentration camp, until liberation by a squad of Allied Forces led by Charles Xavier. They later meet after the war and become friends, and later become rivals. The studio decided to change the film's direction to the early years of the X-Men, but incorporated aspects of Turner's script into the film.
Though ostensibly a prequel to the entire "X-Men" film franchise, this movie deliberately ignores continuity points of X-Men: The Last Stand (2006) and X-Men Origins: Wolverine (2009). Matthew Vaughn explained his intention was to "make a good film that could stand on its own two feet regardless of all the other films" and also that could "reboot and start a whole new X-Men franchise". Writer Jane Goldman looked at the film as an "alternate history" for the X-Men - though a reboot, the writers did not want to go fully "against the canon of the X-Men trilogy", citing the various approaches the comic had in over fifty years of publication.
When Prof Charles Xavier makes his presentation on human genetic mutation at the CIA HQ, the graphic origin of the X-Men logo can be seen in the left hand image of his final side projection. It is an X-ray crystallography image of the DNA molecule, of the kind created by Dr Rosalind Franklin, which aided Dr Francis Crick and Dr James Watson in discovering the double helix shape of DNA on 28 February 1953, for which they were awarded the 1962 Nobel prize for Physiology or Medicine.
According to visual effects supervisor John Dykstra, the biggest problem was with depicting Emma Frost's diamond body "without looking like she was made of Jell-o or the polygon model of a human being". The morphed Frost was rotomated into January Jones in the live-action plates, while still retaining the actress' eyes and lips. As the character kept on going in and out of her diamond form, a motion capture tracking suit could not be employed, so the effects team used a jumpsuit covered in mirrors.
Aware of his character's love connection with Moira McTarget in the comics (in which they're both adults), Caleb Landry Jones tried to look at her "a bit more differently" always when he could on screen, so fans would notice that.
The cities of 1960s Washington and Moscow were created based on photographs of the actual cities; the Russian one in particular had its vehicles and military hardware based on videos of a 1962 Red Square, and a digital army doing an actual Soviet-style march.
Jason Flemyng spent eight weeks with fight training, particularly with swords, and had to undergo a four-hour make-up process, which like Mystique was designed by Spectral Motion-but did not include Azazel's tail, which was computer-generated.
In April 2006 Zak Penn was hired to write and direct this film; he was going to make a prequel about Magneto, in a vein similar to X-Men Origins: Wolverine (2009). However, the filmmakers decided to shift the focus from the early years of one mutant to those of the X-Men. Penn found this approach more interesting than what he'd come up with and so stepped down with his blessing.
Moira MacTaggert uses the call-sign "X-ray Bravo Seven Zero" to identify the X-Men plane. This was the military designation (XB-70) of an experimental nuclear bomber developed in the 1950s, of which two prototypes were built. It was known for its striking, radical design and Mach 3+ speed. The XB-70 was designated "Valkyrie" and was a very sleek, elegant aircraft. Of the two prototypes the first one USAF s/n 62-0001 flew until 1969, when it was placed in the Museum of the United States Air Force at Dayton, Ohio, where it resides today. The second prototype, USAF s/n 62-0207, crashed in June 1966 after a mid air collision. The aircraft the X-Men use more closely resembles an SR-71 Blackbird.
Matthew Vaughn wanted the film to resemble the productions of the 1960s, with "very traditional framing, and camera movement when it needs to move, not just throwing it around and whizz-bang", and using the anamorphic format "to create a widescreen experience, is emblematic of '60s movies". The director had to hire five cinematographers - with sole credit being given to John Mathieson, who came halfway through the shoot and did half of the film - and four assistant directors to successfully convey the look he wanted for the film.
The group of mutants gathered by the CIA in this film serve as a catalyst for the formation of the X-Men which consists of Charles Xavier, Erik Lehnsherr (Magneto), Hank McCoy (Beast), Raven Darkholme (Mystique), Alex Summers (Havok), Sean Cassidy (Banshee) and Armando Muñoz (Darwin). In the comics, the original group of X-Men students consisted of Hank McCoy (Beast), Jean Grey, Scott Summers (Cyclops), Bobby Drake (Iceman), and Warren Worthington III (Angel) - all mentored under Professor Charles Xavier (Professor X).
During a rehearsal, James McAvoy's double, along with all the other doubles, walked on set. The sight of James's double caused him to interrupt rehearsal, walk over to his double, and bear hug him in excitement. This amused Jennifer Lawrence and she said, "Why are you hugging your double like you know him?" James's double on this film was also his double a year prior on The Conspirator (2010).
Matthew Vaughn was originally hired to direct X-Men: The Last Stand (2006), but left citing pressure from the studio to finish the film within too short a time. He was approached again for this movie and accepted, being an X-Men fan with a desire to direct an X-men movie, even though it meant he had even less time to finish the movie than with X-Men: The Last Stand.
Due to it being the off season, and in the middle of a very cold December, there was not a single onlooker during the entire, three week duration of the finale beach shoot. Much to the shock of the crew.
In the scene where Charles Xavier and Raven walk out of a pub into Oxford's New College Lane (the Bridge of Sighs is in the background) they are actually walking out of a side door of Hertford College. The pub sign the filmmakers use is copied from The Eagle pub in Cambridge, where the pioneers of DNA research, where Francis Crick and James Watson announced they had "discovered the secret of life" to some surprised drinkers in 1953. (The pub sign for famous The Eagle And Child pub in Oxford has the bird facing the other way, and is carrying a baby in its talons.)
Many of the palm trees during the finale beach scene kept dying due to the cold, having been shot during December. Space heaters were hidden throughout the beach to keep them warm. Eventually, set dressers had to spray paint the dying palm leaves green to keep up appearances.
In the original comics of the X-Men; the original characters were Angel, Beast, Iceman, Marvel Girl (Jean), and Cyclops. Beast was a strong man with huge feet, whose agility would have matched that of Nightcrawler's.
Beast is the only student from the original X-Men comic to appear in this film. His classmates were Bobby Drake/Iceman, Warren Worthington III/Angel, Jean Grey, and Scott Summers/Cyclops. Scott's brother, Alex, appears in this film and its two sequels. Scott, Jean, and Bobby appeared in all three original films. Beast and Angel didn't appear until the third film, X-Men: The Last Stand (2006).
The scene at the water fountain where Moira "hears" Professor X speaking to her while her co-workers have been frozen, was shot during the final sound mix, on the first floor of building 32 on the Twentieth Century Fox lot.
The X-Men's plane bears a striking similarity to the Lockheed SR-71, an American supersonic reconnaissance plane. However the original plane was not able to depart vertically or even hover in mid-air. It was used for several high-altitude penetration missions deep inside Soviet territory.
This movie initially started out as a spin-off focusing almost exclusively on Magneto's backstory which was meant to be part of a planned X-Men Origins film series, but the idea was then discarded in favour of a prequel that also included Professor X as a major character (he only had a supporting role in the original Magneto script) along with his first class of mutants.
The early version of the X-jet is visually almost identical to the Lockheed SR-71 including the shock diamond effect from the engines. However, the X-jet adds additional engines on the underside for VTOL capability and substantially changes the internal layout from a two person cockpit to a much larger cargo area
The Fast and Furious and X-Men franchises have often released the same installments of a franchise in the same year. X2 and 2 Fast 2 Furious were both released in 2003, X-Men: The Last Stand and The Fast and the Furious: Tokyo Drift were both released in 2006, X-Men Origins: Wolverine and Fast and Furious were both released in 2009, X-Men: First Class and Fast Five were both released in 2011 and The Wolverine and Fast and Furious 6 were released in 2013. Furious 7 was set to be released in 2014, the same year as X-Men: Days of Future Past, however it then was pushed to 2015 after Paul Walker's death.
With Kevin Bacon in this film, there are now 4 actors who have appeared in a famous slasher movie franchise and appeared as a villain in an X-Men film; after Tyler Mane (appeared in X-Men (2000) and Halloween (2007) and Halloween II (2009)), Kelly Hu (appeared in X-Men 2 (2003) and Friday the 13th Part VIII: Jason Takes Manhattan (1989), Liev Schrieber (appeared in X-Men Origins: Wolverine (2009) and Scream (1996), Scream 2 (1997) and Scream 3 (2000)) and Kevin Bacon (appeared in X-Men: First Class (2011) and Friday the 13th (1980)).
Even though the two gentleman share no screen time together both Glenn Morshower and Michael Ironside appear in the film. Both of them have portrayed DC's General Sam Lane. Morshower in Supergirl and Ironside in Smallville.
In Las Vegas during the casino party, the song Palisades Park by Freddy Cannon can be heard playing. One of the lyrics in this song that can be heard clearly is "we ate and ate at a hot dog stand." This may be a reference to the first X-Men (2000) film, in which Stan Lee cameoed as a hot dog vendor.
The call sign that Rose Byrne's Moira MacTaggert uses, X-Ray Bravo Seven Zero (XB-70) was the United States Air Force designation for a prototype super sonic bomber that could fly at Mach 3+ and above 70,000 feet. Two were built in 1964 with one being lost due to a mid-air collision with an F-104 in 1966. The name of the bomber was called "Valkyrie."
The trivia items below may give away important plot points.
Hugh Jackman accepted the opportunity to cameo as Logan the Wolverine when he learned he would be the only character in the film to use the word 'fuck'. He improvised the line, "Go fuck yourself," after using 7 other takes to say, "Fuck off". The reaction from James McAvoy and Michael Fassbender to the different line was authentic.
The ending fight between Charles Xavier and Erik Lensherr was going to have them use their powers, but Matthew Vaughn reasoned that since it was an origin story about the early X-Men the fight had to be a more conventional brawl: "Fox were saying, people want to see super heroes use their powers... but not in this film. Sometimes they just want to punch each other. That, to me, is what's different."
This film's first generation X-Men vaguely mirrors the first generation X-Men from the comics. Whilst Professor X and Beast appear in both incarnations, Havok mirrors Cyclops (they are relatives in the comics), Mystique is somewhat similar to Jean (both knew Professor X before the assembly of the team, both have red hair naturally, both the only female), Banshee has the role of Angel (both being characters with flight and an enhanced sense, Banshee has echolocation and Angel has Binocular vision) and Magneto is similar to Iceman (both are elementalists with Magento controlling Metal and Iceman controlling Ice) Darwin is somewhat similar to Morph. (Both were the first X-Men to die, both possessed Shapeshifting to a certain degree, both attempted to deceive their enemy before their deaths.)