Continuity mistake: The end of the episode shows Xavier standing with no assistance. The only time in the series that the use of his legs were restored were a side effect of him losing his powers. He has his powers in this scene, so there's not really any reason for him to suddenly have the use of his legs back.
Continuity mistake: The position of Cable's gun when it is holstered on his back varies throughout the episode. Sometimes it is slanted at a 45° angle with the butt going over his right shoulder, sometimes it is sticking straight up with the butt going over his left shoulder, etc.
Add timeSerious B
Continuity mistake: When Mystique first impersonates Shard in order to fool Psylocke, both Mystique and the real Shard are missing the gun holster that is usually on top of Shard's right shoulder. When Pyslocke and Wolverine both state that they can see through Mystique's deception, the gun holster has suddenly appeared on Mystique's right shoulder.