The Dark Phoenix (2): The Inner Circle - S3-E12
Other mistake: When Wolverine lands on Leland with his claws extended, if you look closely you'll see that Wolverine's left hand ends up in Leland's chest area, yet Leland was not impaled by the claws like he should have been. (00:17:15)
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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