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.
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 Killer (2012) and was replaced with Matthew Vaughn in May 2010. Singer however stayed on as producer.
The film is based on the "X-Men" comics 'Uncanny X-Men' (1963) and 'X-Men: First Class' (2006).
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 from1963 (their debut) to 2001 (when X-Men (2000) and the Grant Morrison written New X-Men comic inspired a change to black leather).
Director Matthew Vaughn cited the first two X-Films, Star Trek (2009) and the 1960s Bond films as major influences on this film.
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.
Filming was originally to take place on Tybee Island, but a producer browsing on the online map program Google Earth found Jekyll Island to be a more suitable location.
Both Michael Fassbender and James McAvoy appeared in "Band of Brothers" (2001) at the start of their careers. This marks their first appearance together since then.
Casting…what could have been…
Amber Heard was rumored to play Mystique before Jennifer Lawrence was cast.
Taylor Lautner was considered to play Hank McCoy (aka Beast) but dropped out due to scheduling conflicts. Nicholas Hoult was later cast. (Lawd, could you imagine how awful this could've been?)
Rosamund Pike was considered to play both Moira McTaggert and Emma Frost. (Would've been the superior choice over January Jones)
Tahyna Tozzi was considered to reprise her role as Emma Frost from X-Men Origins: Wolverine (2009).
Alice Eve was cast as Emma Frost, but a deal couldn't be reached and January Jones was cast instead.
Sarah Harding was called back three times for the role of Emma Frost.
Charlie Rowe was initially cast as the young Charles Xavier but, due to scheduling conflicts with Neverland (2011) (TV), he was replaced by Laurence Belcher.
Broadway actor Benjamin Walker was previously cast as Beast, but dropped out of the role to star in the Broadway musical 'Bloody Bloody Andrew Jackson'.
Sirs Patrick Stewart and Ian McKellen were considered to appear in the film as the elder Professor X and Magneto, but the idea was rejected as the filmmakers wanted to start a new X-Men trilogy, without any connection to the previous films.
The filmmakers hired an "X-Men" specialist to help the cast understand their roles.
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.
A telepathic battle between Professor X and Emma Frost was going to be in the film, but upon the release of Inception (2010) the concept was scrapped.
Michael Fassbender, who plays the Jewish Holocaust survivor character Magneto in this film, had earlier played an Allied Forces soldier in Inglourious Basterds (2009). Paradoxically and ironically, Sir Ian McKellen, who also played Magneto, had earlier played a Nazi in Apt Pupil (1998) (thus going the other way from Fassbender).
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."
To prepare for his role as Beast, Nicholas Hoult studied Kelsey Grammer's performance as Beast in X-Men: The Last Stand (2006) and Grammar's early series "Frasier" (1993); he also underwent training in athletics, weightlifting and boxing.
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 MacTaggart would not have her trademark Scottish accent in the film (to the Scottish McAvoy's mild disappointment).
I loved the movie and think it's up there with X2 however no movie is without its flaws. Flaws like January Jones, Zoe Kravitz role, Mystique's makeup, some of the CGI, and I'm sure there's a few more but I can't think of them right now...