Continuity mistake: When Beast and Dr. Bohlson enter Carly's room, there is no breast pocket on Dr. Bohlson's labcoat. A couple of shots later, his labcoat now has a breast pocket with two tongue depressors in it. (00:02:25)
Continuity mistake: When the opening of the Astral Plane is first shown emerging from Mt. Kilimanjaro's Kibo summit, the summit is correctly depicted as being somewhat flat. Near the end when the opening of the Astral Plane is diminishing, the mountain summit is shown to have a pyramidal peak. (00:02:35 - 00:16:50)
Continuity mistake: The boomerang that Xavier uses to throw at the jungle warrior astride the pterodactyl appears from nowhere. While it probably belonged to the warrior himself, neither he nor the other warrior with him were shown to have dropped it when they swooped by and captured Magneto and knocked Xavier down. (00:20:15)
Continuity mistake: When Wolverine falls down the mine shaft, debris is shown to be falling with him. A few shots later, there is no debris to be seen on the ground where he landed. (00:13:15)
Continuity mistake: Storm's eyes alternate between being brown and blue throughout the episode.
Continuity mistake: When Storm and Rogue are flying towards Storm's village in Tanzania, at one point Storm's hands are colored white. (00:05:25)
Continuity mistake: The graphic of Africa that Beast and Jean are observing is horizontally stretched at one point. (00:02:50 - 00:03:50)
Continuity mistake: When Gambit places Bella Donna's ring on the ground, she is nowhere around it. When the shot changes, the ring is suddenly right next to her. Note: this mistake may only apply to the DVD version of the episode, as the version of the episode on Disney+ does have Bella Donna there when Gambit sets the ring down. (00:18:50)
Continuity mistake: When the External states the Guild of Thieves have dishonored the tithe, both the Thieves' and Assassins' tithe boxes are missing from their respective tree stumps. (00:17:10)
Continuity mistake: When the External is emerging from the water, the Thieves Guild's tithe box is missing from its respective tree stump. In the next shot, it is back in place. (00:16:30)
Continuity mistake: When Rogue flies back towards Gambit and Bella Donna, Bella Donna is standing behind Gambit. When the shot changes, Bella Donna is standing in front of Gambit. (00:15:35)
Continuity mistake: When the Thieves and Assassins guilds begin to skirmish, they start by trying to regain the weapons that Jean Grey telekinetically confiscated from them. A couple seconds into the fight and most of the weapons have disappeared altogether. (00:15:20)
Continuity mistake: When Gambit pushes Bella Donna over, she is on his left, and there is a tree stump on his right (out of shot). When the shot changes, she is up against the tree stump. (00:14:25)
Continuity mistake: When Gambit is looking at himself in the mirror while wearing a tuxedo, you can see in his reflection that he is barehanded. In the next shot when he removes the tuxedo, he is wearing his usual black gloves. Also, the rose on the tuxedo goes from being on his right side (reflection's left) to being on his left side just before he removes the tuxedo. (00:13:15)
Continuity mistake: In the first establishing shot of the Assassins Guild's mansion, there is a stairway leading up to the front door. In the establishing shot of the mansion in the scene where Gambit is in Bella Donna's bedroom, the stairway is missing, and consequently the mansion's porch area isn't as high off the ground. (00:09:20 - 00:13:20)
Continuity mistake: The cell that Bobby was held captive in is noticeably smaller after he is set free. (00:09:55 - 00:11:40)
Continuity mistake: After Bobby is set free, Gambit, Bella Donna and her henchman remain in Bobby's cell. When Bella Donna begins torturing Gambit, the two of them are suddenly alone in the cell. (00:11:20)
Continuity mistake: When Bobby starts walking out of his cell, Gambit has his back to him. When the shot changes, Gambit is suddenly facing him. (00:11:15)
Continuity mistake: The two assassins standing guard outside the Assassins Guild's mansion have swapped sides when they let Gambit in the front door. (00:09:25)
Continuity mistake: After Jean Grey, Rogue and Wolverine locate Gambit's mini-jet, they land the Blackbird behind a row of plants. When they emerge from the Blackbird, the plants have disappeared. (00:08:55)
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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