The Phalanx Covenant: Part 1 - S5-E1
Continuity mistake: When Mr. Sinister blasts the Phalanx-civilians, his gloves are red. A couple of shots later, his gloves are their usual blue. (00:17:50)
The Phalanx Covenant: Part 1 - S5-E1
Continuity mistake: When Beast says "And we waited until you arrived," his eyebrows keep changing from blue to black. (00:16:10)
The Phalanx Covenant: Part 1 - S5-E1
Continuity mistake: When Beast replays the video of Warlock's tissue sample assimilating the metal, the human and mutant tissue samples on the left have disappeared. (00:11:35 - 00:12:30)
The Phalanx Covenant: Part 1 - S5-E1
Continuity mistake: When Beast is trying to escape the Phalanx in Wolverine's jeep, he has to drive down a considerably long road just to reach the gates to the mansion. In all previous episodes, the road leading to the mansion is barely longer than a driveway. (00:08:35 - 00:09:10)
The Phalanx Covenant: Part 1 - S5-E1
Other mistake: As usual, Wolverine's jeep is missing its windshield. (00:08:25)
The Phalanx Covenant: Part 1 - S5-E1
Revealing mistake: When Beast lunges away from the Phalanx disguised as several people in hazmat suits, after he lands he glides across the grass. (00:08:15)
The Phalanx Covenant: Part 1 - S5-E1
Continuity mistake: When Beast is running from the Phalanx through the mansion's hallways, his trunks go from being Speedo-like to resembling basketball shorts. (00:06:50)
The Phalanx Covenant: Part 1 - S5-E1
Continuity mistake: When Wolverine lunges at Sabretooth, his normally-red belt is colored yellow. (00:04:55)
The Phalanx Covenant: Part 1 - S5-E1
Continuity mistake: When Wolverine confronts Sabretooth in his holding cell, Wolverine's face is colored yellow. (00:04:25)
The Phalanx Covenant: Part 1 - S5-E1
Continuity mistake: When Jubilee accidentally lets slip that Sabretooth is in the mansion in front of Wolverine, the hand portions of her gloves disappear. (00:03:00)
The Phalanx Covenant: Part 1 - S5-E1
Audio problem: When Sabretooth is holding up the two cops, one of them says "Put me down! Put me down!" But neither of them are moving their mouths. (00:01:45)
The Phalanx Covenant: Part 1 - S5-E1
Continuity mistake: When Sabretooth is terrorizing the police and civilians, it is broad daylight outside. When Beast and Jubilee are shown approaching the scene in the Blackbird just before dispersing tranquilizing gas, it is twilight. (00:01:00 - 00:01:50)
The Phalanx Covenant: Part 1 - S5-E1
Revealing mistake: The shot of police cars surrounding Sabretooth and him throwing one of them into the air is a recycled shot of the very first shot in the series from the season 1 episode "Night of the Sentinels, Part 1." It's even revealed a few minutes later in the episode that this isn't actually Sabretooth, but a Phalanx facsimile that has taken his form, which makes the fact that Sabretooth's actions are being recycled all the more dubious. (00:01:35)
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.
BaconIsMyBFF