The Lotus and the Steel - S4-E13
Deliberate mistake: Every native of the Japanese village that Wolverine visits is conveniently fluent in English, and they even speak English to each other when no other people from English-speaking countries are around. (00:04:45 - 00:20:45)
Deliberate mistake: The security footage of Proteus' escape from the Muir Island Research Facility is merely the same earlier scene played over again. (00:06:50)
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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