Days of Future Past: Part 2 - S1-E12
Character mistake: After Gambit escapes from Wolverine and Bishop, Bishop says to Wolverine "No wonder you sent me back to change the future, because everything that happens is your fault." Wolverine didn't send Bishop back to change the future. He insisted on going back himself, but Bishop forced Wolverine out of the mission and inserted himself into the role because he felt Wolverine was too old to succeed. (00:10:03)
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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