Continuity mistake: When Gambit is asking why Cyclops wants his Danger Room session to be tougher, there is a microphone a few inches from his mouth. When the shot changes, the microphone has disappeared. (00:02:44)
Continuity mistake: When the Danger Room monster has ensnared Cyclops, the slime coming off its tentacles is green. When the shot changes, the slime is orange. (00:02:18)
Other mistake: Julianne Klemm, the writer for this episode, has her first name misspelled in the opening credits as "Julaianne." (00:02:07)
Audio problem: When Barbarus says "Get them!" he says the word "them" without closing his mouth. It's not possible to say "them" without closing your mouth at the end of the word. (00:20:10)
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)
Other mistake: When Gambit pushes Bella Donna down, the wedding veil that she was wearing comes to a stop in midair. (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)
Other mistake: When Wolverine is threatening Pierre, there is a continuous shot lasting roughly 8 seconds in which Bobby is telling Rogue about Bella Donna, all the while Wolverine and Pierre remain in the foreground, and neither of them so much as moves a muscle in that 8-second span. Rogue also remains motionless for a majority of the shot. (00:13:35)
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)
Revealing mistake: When the assassin is handing Bobby the tithe box, the assassin's left hand passes through the chair Bobby was sitting in. (00:11:15)
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)
Other mistake: When Bella Donna's henchman is letting Bobby go, he is shown to be walking over to Bobby empty-handed. After he unties Bobby, the tithe box has magically appeared in his hands. (00:11:10)
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)
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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