Continuity mistake: When Pierre is waiting for Gambit in his boat, there is another boat next to his. When he and Gambit take off, the second boat has disappeared. (00:07:55)
'Til Death Do Us Part: Part 1 - S2-E1
Continuity mistake: Beast disarms a member of the Friends of Humanity whilst perched on a street lamp. When the angle changes to a wide shot, Beast is much higher on the lamp post and would have been too far out of reach to disarm the man in the first place. (00:11:45)
'Til Death Do Us Part: Part 1 - S2-E1
Other mistake: When Wolverine, Gambit and Beast are battling members of the Friends of Humanity, Wolverine slices through the gun of one of their members. From the angle Wolverine is standing respective to the F.O.H. member, he could not have possibly sliced through the gun without also slicing off the man's left hand. (00:12:00)
Continuity mistake: The exploding playing card that Gambit uses to destroy a few Sentinels and draw the rest above ground is cleverly shown to be the ace of spades (also known as the death card in some folklore), but the card he is shown charging up before the Sentinels see it is the 2 of diamonds. (00:12:10)
Continuity mistake: When Gyrich is in the car trying to get Trask on the phone, he is shown to be sitting in the backseat on the passenger side (note the windows immediately to his right and behind him). When his driver crashes the car into a tree, Gyrich is shown exiting the car from the front passenger seat. (00:08:00)
Continuity mistake: When Wolverine is searching for Sabretooth and the captive Inuits, his arms suddenly turn yellow. (00:15:50)
Continuity mistake: When Archangel is lamenting his actions, the communicator devices from Storm's uniform are missing. (00:20:15)
Continuity mistake: When the three horsemen are climbing onto their mechanical horses, Famine's horse is in the middle, and Pestilence's horse is on the right. Once all three have all been individually shown to be mounting their horses, Famine and Pestilence have swapped places. (00:06:08)
Continuity mistake: When Gambit is saying "Someone may be tracking us," the snaps on both shoulders of his jacket are colored blue, when they should be the same brown color as the rest of his jacket. (00:11:45)
Continuity mistake: When Gambit first walks into Bobby's cell, Bobby is sitting in a chair up against the back wall. A few shots later, Bobby is sitting in the center of the cell. (00:09:55)
Family Ties - S4-E17
Revealing mistake: When Quicksilver is fidgeting inside his containment shell, the animators neglected to properly sync his body movement. You can see that his shoulders are not "connected" to his arms, as if his head and shoulders were separated from the rest of his body. (00:16:00)
Beyond Good and Evil: Part 3 - S4-E10
Continuity mistake: When the Four Horsemen are retreating back into the pyramid, the opening is shown to be illuminated. When they are shown entering the opening, it is in darkness. (00:17:15)
Beyond Good and Evil: Part 2 - S4-E9
Continuity mistake: Magneto straps Wolverine to the port side of a boat and then drops the boat on a warehouse. When Gambit is freeing Wolverine, Wolverine is suddenly on the starboard side of the boat. After Gambit frees Wolverine, they are both shown to be on the boat's port side. (00:17:00 - 00:18:00)
Weapon X, Lies, and Video Tape - S3-E19
Continuity mistake: The helmet Wolverine picks up changes from gray to gold and then back to gray when he drops it. (00:05:25)
Continuity mistake: Gambit moves further away from Rogue when they are sitting on the couch. (00:03:00)
Continuity mistake: The tray of food Beast brings for Iceman has suddenly disappeared when he asks him about Lorna. (00:09:20)
The Phoenix Saga (2): The Dark Shroud - S3-E4
Continuity mistake: When Gambit is getting ready to attack Dark Xavier, the ticket booth behind him is unoccupied. When Dark Xavier deflects Gambit's kinetically charged playing card to the ticket booth counter, a man is now inside the booth. The bottom center window also goes from being closed to being open. (00:12:16)
The Phoenix Saga (2): The Dark Shroud - S3-E4
Continuity mistake: The tops of Juggernaut's boots change from brown to orange after he bursts into Professor X's room. (00:20:30)
The Phoenix Saga (2): The Dark Shroud - S3-E4
Continuity mistake: When Cyclops and Wolverine bring Jean back above the water surface, her wet hair is pointing straight down. When the shot changes, her hair is suddenly wavy and parted over her forehead. (00:05:00)
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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