Continuity mistake: Cocteau's tombstone has gained a gold plate on the front of it by the end of the episode. (00:01:35 - 00:19:25)
Continuity mistake: When Wolverine is saying "You cheated me, old man!", the lower half of his trench coat briefly changes color. (00:01:40)
Continuity mistake: When Wolverine and Captain America start running, they are standing very close to each other. When the shot changes, they are several feet apart. (00:06:50)
Continuity mistake: When Wolverine and Captain America first find Cocteau, the white ring on Captain America's shield is colored black in a wide shot. (00:08:45)
Continuity mistake: When Wolverine causes Cocteau to faint, his glasses fall off. When the shot changes, the glasses are nowhere to be seen on the ground. (00:09:05)
Continuity mistake: When the Nazis begin to surround Wolverine and Captain America, a group of them are shown to be coming through a door and into a very large room, despite the fact that the scene is actually taking place inside a narrow corridor. (00:09:50)
Continuity mistake: When Red Skull is leaving Wolverine and Captain America alone, he sets Captain America's shield on a table and Wolverine is shown to be hanging from stocks by his wrists with Captain America on his left and the table on his right at roughly a 45 degree angle. In a wide shot after Red Skull has left the room, the shield has vanished from the table and Wolverine is now several feet from where he originally was, with Captain America roughly at his 12 o'clock and the table roughly at his 3 o'clock. (00:10:45)
Continuity mistake: When Captain America says "Red Skull, wait!", his sleeves are entirely blue whereas they should be white from the mid-bicep and down. (00:10:45)
Continuity mistake: The Red Skull punches Captain America's shield with his left hand, but then shows pain in his right hand. (00:13:10)
Continuity mistake: Wolverine's gloves have suddenly disappeared after the robot is destroyed,. (00:15:05)
Continuity mistake: After Wolverine carves "HERO" onto Cocteau's tombstone, he has to walk several feet away from the tombstone to get to Justine. When the shot changes, both of them are only a couple steps away from the tombstone. (00:19:15)
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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