Other mistake: When Rogue rendezvous with Beast, Xavier and Gambit, she pinches Gambit's cheek with her bare fingers. This should have caused her to drain his powers and render him unconscious. (00:14:10)
Other mistake: When Gambit pushes out the vent shaft cover from inside the ventilation system, his hands emerge gripping the outside of the cover. This would be physically impossible. (00:09:55)
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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