Secrets, Not Long Buried - S4-E15
Continuity mistake: During the battle at the end, Cyclops uses the crystal statue he brought with him in the fight by throwing it into the air and uses it to refocus his optic blasts on a crowd of attackers. After the battle is over he gives the statue to Dr. Prescott without ever having retrieved it. (00:18:55 - 00:20:20)
Secrets, Not Long Buried - S4-E15
Continuity mistake: The mutants that have gathered for Solarr's speech are in different places throughout depending on the shot. (00:16:50 - 00:18:50)
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