Many other directors who were considered to direct the movie included Richard Donner, John McTiernan, Danny Boyle, Stephen Hopkins, Joel Schumacher and Irvin Kershner.
Christopher Lee was considered for the part of Magneto.
Gary Sinise was the studios preferred option for the role of Wolverine.
This is the first film based on a marvel comic that Stan Lee provides a cameo for.
# # When Logan complains about the X-Mens' uniforms, Cyclops replies "Would you prefer yellow tights?" This is a reference to the original X-Men comic, in which Wolverine's uniform consisted of yellow tights.
Screenwriter Andrew Kevin Walker wrote a draft of the screenplay, but with a different team of X-Men (Professor X, Cyclops, Jean Grey, Beast, Iceman, Angel, and new member Wolverine) and a different team roster for the Brotherhood of Mutants (Magneto, Toad, Sabretooth, Juggernaut, and new member Blob). Walker's draft was never used, but some of his dialog and scenes were included in the official novel adaptation books sold in stores.
The scene is the train station where the young boy smiles at Cyclops, and Cyclops smiles back was unplanned. The boy was a huge fan of the X-Men, and Cyclops was his favorite. The scene originally called for Cyclops to look at the train schedule, however, according to Bryan Singer, the boy could not stop smiling at James Marsden (the actor playing Cyclops). Finally, during one shot, Marsden just looked back at him and smiled, much to the boys delight. Bryan Singer liked the idea so much, he kept it in the film, and told the actress playing the boy's mother to react the way she did.
Although he's reasonably tall, James Marsden, who plays Cyclops, had to stand on an apple box to appear taller next to one of the boys in the train station. As a prank, Tyler Mane, who plays Sabretooth, went into Marsden's trailer and set an apple box in his bathroom with a note - "This is so you can reach your sink."
Tim Burton was approached by a 20th Century Fox to direct the movie but opting to direct Mars Attacks! (1996) instead.
James V. Hart Walker was hired to write the script in 1994, but it was never used for the film.
Look for James Marsden's platform shoes as he scales the wall at Liberty Island, after leaving the X-Jet.
WWE wrestler Kevin Nash was offered the role of Sabretooth, but he turned it down due to schedule conflicts.
Bryan Singer cast Halle Berry as Storm after seeing her performance in Introducing Dorothy Dandridge (1999) (TV).
Near the end, during the Wolverine/Mystique fight scene, there is a moment where Mystique kicks Wolverine in the groin. At that moment, there is a metallic 'ping' (similar to the one in the beginning when the man in the cage match punches Wolverine's fist), which is probably an 'in-joke' to Wolverine having 'balls of steel' (or in this case, adamantium).
Rebecca Romijn and Sam Elliot have both played major and supporting roles as different characters throughout the Marvel Universe. Sam Elliot played a major role as General Ross in Hulk, and a supporting role as the Caretaker in Ghostrider. Rebecca Romijn had a major role as Mystique in all 3 X-Men movies, and played a supporting role as Joan (Frank's neighbor) in The Punisher.