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)
Audio problem: When Wolverine says "In a toxic nuclear powder keg," his mouth is not moving. (00:08:10)
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)
No Mutant Is an Island - S5-E4
Audio problem: Governor Barker has the exact same voice as President Kelly. (00:04:20)
Audio problem: When Storm says "I command the Sahara Winds," her mouth is completely still for the last two words. (00:04:00)
Audio problem: When Wolverine says "Now move over!", you can see his reflection in the truck's windshield and his mouth is completely closed. (00:07:00)
Audio problem: When Jubilee says "I think," her lips are completely pressed together for the word "think." Saying "think" would require a person to touch their tongue to their teeth and lips apart. (00:13:15)
Audio problem: When Cyclops says "I hope they weren't from the Chamber of Commerce," his mouth is completely closed. (00:14:50)
Audio problem: When Jubilee says "But look, I think that Arkon guy really likes Storm," her mouth is completely closed for the words "I think that Arkon." (00:18:40)
Audio problem: The sound of the slave shrieking in terror is recycled from previous episodes where Morph would make the same sound (for example the season 4 episode "Courage" and any of the five episodes he appeared in during season 2). (00:02:30)
Audio problem: When the bearded warrior says "They await only the order to strike," his mouth is completely closed. (00:04:40)
Audio problem: When Arkon says "We attack tonight," his mouth movement is slightly out of sync with the dialogue. (00:05:45)
Audio problem: Cyclops' mouth is completely closed when he says "Get your nose ready Logan." (00:07:20)
Audio problem: When Arkon says "As you wish, beloved," his mouth is slightly out of sync with the dialogue. (00:08:40)
Audio problem: When Storm is saying "No, stop this madness! Cyclops, Logan..." her mouth is completely closed when she says "Cyclops." (00:16:55)
Jubilee's Fairy Tale Theater - S5-E9
Audio problem: The troll-Wolverine's mouth is closed when he says "We got the trinket, but what do we do with it?" (00:12:30)
Audio problem: When Mr. Guthrie is saying "I worked with you inside the mines and shopped in your stores," his mouth is completely out of sync with the dialogue, sometimes not even moving at all. (00:14:45)
Audio problem: When Magneto is saying "I have heard your cries for justice and I now answer that call," his mouth is not moving. (00:11:45)
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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