Night of the Sentinels: Part 1 - S1-E1
Character mistake: When Jubilee wakes up in the infirmary, the sphygmomanometer on her wrist has been applied over her gloved hand, which could cause a false reading. Beast is the X-Men's resident doctor, so presumably he's the one that applied it to her, so he should have known to remove her gloves first for more accurate readings. (00:08:24)
Night of the Sentinels: Part 2 - S1-E2
Character mistake: When Beast is uploading the virus to delete all the mutant files from the computer, Storm destroys the monitor with a bolt of lightning and says they have run out of time. Destroying the monitor wouldn't magically erase the files. While she may not know that, Beast definitely would, so at the least, he should have asked her to destroy the computer tower and hard drive as well. (00:06:13)
Character mistake: When Rogue asks Storm what her plan is for dealing with the closing walls, Storm says "You three stop the walls, I shall slow the ceiling." Besides Storm and Rogue, Jubilee, Jean Grey, and Gambit are also there, so Storm should have said "You four stop the walls." (00:03:12)
Days of Future Past: Part 2 - S1-E12
Character mistake: After Gambit escapes from Wolverine and Bishop, Bishop says to Wolverine "No wonder you sent me back to change the future, because everything that happens is your fault." Wolverine didn't send Bishop back to change the future. He insisted on going back himself, but Bishop forced Wolverine out of the mission and inserted himself into the role because he felt Wolverine was too old to succeed. (00:10:03)
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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