After "The Phoenix Saga" aired, the remaining episodes that aired were not in the correct continuity order. Because the bulk of episodes were being animated with many different studios, the writers decided not to continue with linear storylines like the first two seasons, as many would likely air as soon as they became available. Continuity problems became so bad that episode 3.8 "No Mutant is an Island" and episode 3.10 "Longshot" did not air for two years after they should have, thanks to animation quality issues. "No Mutant is an Island" was *supposed* to explain Jean Grey's return, setting up the Dark Phoenix Saga.
Due to late development for the first season, episode 1.08 "The Unstoppable Juggernaut" aired after episode 1.09 "The Cure" and episode 1.10 "Come the Apocalypse" during the first run. Because of this, a quick animation fix with re-edited footage was created for the original airing of episode 1.09 "Slave Island", showing the X-Men returning home to the Mansion and the Blackbird landing.
Sidney Iwanter, an executive at Fox, originally planned on "ending" the series with a big bang ("Beyond Good and Evil - parts 1-4"). We even had planned to have characters leaving the team at the conclusion, but at the last minute Fox asked for more episodes. Unfortunately, at the time Marvel was filing for bankruptcy and could not afford to produce more episodes, so Saban funded them directly. This explains why the last six episodes looked different than the previous 70. So the show officially "ended" things again with "Graduation Day."
The voice actors were largely cast from the Toronto theater scene.
Fox initially had a lot of resistance to the cartoon series before it became a success. They felt that the target audiences, kids under 10, wouldn't be interested in a romantic love triangle between Cyclops, Jean, and Wolverine. They also thought kids wouldn't keep up with a show that was serialized.
Stan Lee was not creatively active with Marvel comics at the time the series was being produced so his involvement wasn't particularly big on the series. He gave some producers notes on the first thirteen episodes
The series adopted a number of famous storylines and events from the "X-Men" comics.
After the box office success of X-Men in the summer of 2000, Fox briefly aired reruns of the cartoon on weekday afternoons (at first they only broadcast episodes that primarily featured content in the movie, but later the series was aired in proper order).
The series artwork and X-Men roster were based on comic book artist Jim Lee's "X-Men" comics. Around the time of the series production, Lee was working on the comic series "X-Men: Legacy" (then called simply "X-Men"), which was ranked by the Guinness Records as the best-selling comic of all time.
The sound effect used for Magneto's magnetic powers is the same sound effect used in Star Trek III: The Search for Spock for the Klingon cloaking device.
David Hemblen (the voice of Magneto in the show) was offered the chance to play Magneto in the X-Men live action movie. Hemblen wanted the role but he was forced to turn down the role due to scheduling conflicts with his show Earth: Final Conflict.
The first time that "People fear what they don't understand" is mentioned.
The creators of the show have altered the way Jubilee joined the X-Men. In the comic books, Jubilee met Dazzler, Storm, and Rogue in a shopping mall. In the issue, she made her way through Gateways portal back to the X-Men's base in the Australian Outback. As featured in Uncanny X-Men #244.
DEBUT: Cyclops, Wolverine, Storm, Rogue, Beast, Jubilee, Gambit, Jean Grey, Professor X, Robert Kelly, Morph, Henry Gyrich and the Sentinels.
In the comic books, the Sentinels were introduced in X-Men (v1) #14. In addition, they were originally shown to be only slightly bigger than a normal human.
DEBUT: Bolivar Trask.
Jubilee is shown putting on her sunglasses before using her powers. This happened quite often during the series, hinting that Jubilee can be blinded by her own powers.
The president of the USA is shown as being a woman.
Gambit and Rogue do not appear in this episode.
Gambit and Beast do not appear in this episode.
In the comic version of the fight between Storm and Callisto, they dueled with knives instead of staves.
DEBUT: the Morlocks.
Original airing, the episode ended with the X-Men arriving at an intact X-Mansion. Due to Animation delays/ problems with "The Unstoppable Juggernaut/Cain Marko", the ending was altered since the Juggernaut/Cain Marko episode would not be ready to air for some time.
DEBUT: Northstar and Aurora of Alpha Flight.
DEBUT: Cable/Nathan Dayspring-Summers.
Northstar/Jean-Paul Beaubier and Sunfire/Shiro Yashida were two of the mutant captives in Genosha.
This episode features the first appearances of Juggernaut (Cain Marko) and Colossus (Piotr Rasputin).
This episode features the first appearances of Apocalypse (En Sabah Nur), Angel (Warren Worthington III), and Moira McTaggert. Pyro, Avalanche, and Mystique make their first full appearances, after cameos in "Slave Island" and others.