Trivia: According to the book "Previously on X-Men: The Making of an Animated Series," this episode was originally conceived as an episode called "Bring Me Charles Xavier" (a reference to the film Bring Me the Head of Alfredo Garcia), and would have been the 47th episode of the series overall. In addition to the return of Omega Red, it also would have seen the returns of Colossus and his little sister Ilyana, as well as Darkstar. The episode was written by showrunner Eric Lewald, and after being told numerous times by his colleagues that the script just didn't work, he reworked it into what became this episode. An image for the cast list of the unproduced episode is visible in the book "X-Men: The Art and Making of the Animated Series."
Bloodlines - S5-E6
Trivia: The trick-or-treaters that show up to the mansion are dressed up as Spider-Man, Daredevil and the lesser-known Devil Dinosaur. (00:03:15)
The Phalanx Covenant: Part 1 - S5-E1
Trivia: This episode has a similar plot to "Invasion of the Body Snatchers," and in particular the scene where Warlock deduces that President Kelly has been assimilated by the Phalanx because he knew of Warlock's association with Beast without Beast having told him is a reference to the 1978 film where it is deduced that the police are pod people when they acknowledge the name of Donald Sutherland without him having told them. (00:13:05)
Answer: Chris Potter, the original Gambit voice actor, did indeed quit the role in the 4th season. His last episode was The Phalanx Covenant Part 1 so it seems reasonable that Fox would limit the use of the character even though it was recast. It doesn't appear that Potter left the role due to animosity, he stated in an interview that he wished to play Gambit in the first live action X-Men film.
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