Beyond Good and Evil: Part 1 - S4-E8
Revealing mistake: When Mr. Sinister is mocking Jubilee, take a close look at his neckline as he moves his head. The animators moved his neckline as he moved his head, but his shoulders stay in place, so his head and neck look like they are floating above his shoulders. (00:15:30)
Beyond Good and Evil: Part 1 - S4-E8
Revealing mistake: The slice of cake that Wolverine cuts out already has the cut-lines animated on it before he starts slicing it. Probably to make it easier for the animators to animate his hand movement. (00:11:05)
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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