Continuity mistake: Nightcrawler gives Wolverine a bible, yet he never had the bible on his person before giving it to him. (00:18:55 - 00:19:35)
Continuity mistake: The monks give Rogue a robe to wear over her tattered ski suit. When she says she needs to go check on Gambit, she is suddenly not wearing the robe. (00:07:00 - 00:07:50)
Continuity mistake: When Rogue walks in on Brother Reinhardt attempting to kill Gambit, she goes from being gloveless to wearing blue gloves depending on the shot. (00:08:20)
Continuity mistake: When Rogue is attempting to rescue Gambit from the avalanche, Gambit's right hand goes from being gloveless to gloved. There is even a point when she is pulling him out of the snow that a glove instantaneously materializes on his hand and then disappears just as quickly. (00:05:20)
Continuity mistake: Gambit is gloveless when he is lying in the snow. When he falls downhill, he is suddenly wearing gloves. (00:04:35)
Weapon X, Lies, and Video Tape - S3-E19
Continuity mistake: When the X-Men are standing around Wolverine, the back of Cyclops' head gear is the same color as his hair. (00:01:35)
Weapon X, Lies, and Video Tape - S3-E19
Continuity mistake: When Professor Oyama is stating how he intends to test his adamantium bonding process on Wolverine, if you look closely you can see that Wolverine already has adamantium claws protruding from his hands. (00:13:20)
The Juggernaut Returns - S3-E17
Continuity mistake: When Wolverine is saying "Make your move tough guy," to Juggernaut, Cyclops' gloves are the same color as the ground and his normally yellow belt is red. (00:20:25)
The Juggernaut Returns - S3-E17
Continuity mistake: When the new Juggernaut is falling towards the film studio, he is shown to be falling at a diagonal angle. When he crashes through the ceiling, he is falling straight down. (00:16:10)
The Juggernaut Returns - S3-E17
Continuity mistake: When Gambit is repairing the school bus, his sleeves are pink with blue patches when they are normally black with pink patches. (00:06:10)
The Juggernaut Returns - S3-E17
Other mistake: During the "Previously on X-Men..." segment before the show's intro, it shows the Juggernaut landing in the ocean and walking across the ocean floor after Gladiator had hurled him away. However, Juggernaut's fate was never actually shown after Gladiator threw him. He was only seen fading off into the distance. (00:00:50)
Other mistake: When Corsair is running towards the Starjammers and Storm at the top of the Mayan structure, Lilandra can be seen among the group despite the fact that she was not in the episode before or after this moment. This was most likely supposed to instead be Jandra, the Shi'ar child that the Starjammers were trying to protect. (00:18:50)
Continuity mistake: After Storm is caught in a net and uses a lightning bolt to burn a hole in it, the net has magically disappeared altogether in the next shot. (00:14:30)
Continuity mistake: When Cyclops is telling Raknar that he hasn't agreed to anything, the back of Raknar's head is flesh-colored when it is shown to be black throughout the episode. (00:14:00)
Continuity mistake: Corsair's normally brown eyebrows and mustache are suddenly black when Cyclops is asking him if he would have come back for him and his brother had he known they were alive. (00:11:10)
Continuity mistake: Cyclops' gloves disappear when he jumps off the pier. (00:04:10)
Continuity mistake: The airplane passenger reading the newspaper goes from being in an aisle seat to a window seat. (00:02:15)
Continuity mistake: When Professor X is apologizing to Iceman, there is a red contour line on the side of his hoverchair that wasn't there before. (00:18:05)
Continuity mistake: Iceman's ice form alternates between being transparent and solid throughout the episode.
Continuity mistake: Strong Guy completely disappears from the screen after the water tower falls on him. (00:17:25)
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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