One Man's Worth: Part 1 - S4-E1
Other mistake: Shard shows Storm and Wolverine surveillance footage of Trevor Fitzroy's deal with Master Mold, stating it was all they could get of their plan before the camera was discovered. However, the footage shows multiple camera angles that a lone mounted surveillance camera could not achieve. (00:11:30 - 00:12:35)
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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