No Mutant Is an Island - S5-E4
Audio problem: When Professor X is saying "We all know the risks of being an X-Man," his face freezes with his mouth open mid-sentence. (00:01:30)
Audio problem: When Wolverine says "In a toxic nuclear powder keg," his mouth is not moving. (00:08:10)
The Phalanx Covenant: Part 1 - S5-E1
Audio problem: When Sabretooth is holding up the two cops, one of them says "Put me down! Put me down!" But neither of them are moving their mouths. (00:01:45)
Family Ties - S4-E17
Audio problem: When the High Evolutionary says "The Scarlet Witch possesses the mastery of probability," his mouth is completely closed. (00:13:30)
Family Ties - S4-E17
Audio problem: When the High Evolutionary claps his hands, there is no corresponding sound. (00:08:25)
Audio problem: Wolverine's mouth is closed when he says "Man, the weird dream I just had." (00:13:35)
Secrets, Not Long Buried - S4-E15
Audio problem: When Solarr, Chet and Toad are laughing at Cyclops, the sound of their laughter begins about a second before they actually start laughing. (00:11:45)
Secrets, Not Long Buried - S4-E15
Audio problem: After Cyclops crash lands, the shot changes to Watchdog observing the crash on his monitor with a voice-over saying "Scratch one trouble maker," except that the voice speaking is that of Solarr and not Watchdog.
Audio problem: When Wolverine says "I'm going to get this outta me!" his mouth is wide open for most of the line. (00:14:05)
Audio problem: With the exception of the last word in the sentence, Cody's mouth is completely closed when he says "They need us Rogue, just like I need you." (00:13:40)
Beyond Good and Evil: Part 4 - S4-E11
Audio problem: After Bender reverts to his true form of Immortus, he laughs before disappearing. The laugh is oddly inaudible on the DVD. (00:18:50)
Beyond Good and Evil: Part 3 - S4-E10
Audio problem: After Bishop says "It's Cable!", Bender says "It will be..." except Bishop is the one mouthing the line. (00:02:55)
Beyond Good and Evil: Part 2 - S4-E9
Audio problem: When Magneto says "I see I must persuade you," his mouth is completely closed. (00:16:30)
Beyond Good and Evil: Part 2 - S4-E9
Audio problem: When Xavier says "Assemble the X-Men," his mouth movement is slightly out of sync. (00:05:55)
Audio problem: When Fabian Cortez says "Mark my words X-Man. Before this day is done you will beg me to let you join us," his mouth movement is out of sync with the words "is done." (00:05:40)
Audio problem: Beast's mouth is wide open when he says "Feet don't fail me now." (00:02:05)
Audio problem: When Xavier is saying "I fear Magneto may come to depend upon it like a drug," Beast is actually the one mouthing the line. (00:14:15)
Audio problem: Fabian Cortez's mouth is closed when he says "Lord Magneto." (00:10:15)
Audio problem: Magneto's mouth is closed when he says "The mutant race will no longer be managed, mister delegate." (00:02:20)
Audio problem: The amount of crowd noise during Joe McTaggert's speech is inconsistent with how many people are shown in attendance. The noise would suggest at least a couple hundred people, but shots of the crowd only show a few dozen. (00:08:25 - 00:10:20)
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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