Plot hole: After Storm's attempt to escape the Genoshan prison is thwarted, she ends up in the ocean right at the shoreline of the beach, where she is captured by a Sentinel. Aside from the fact that it makes no sense for a Sentinel to be hiding in the ocean in the event that a mutant tries to escape the prison, there is absolutely no way that a two-story tall robot could hide in the ocean right by the beach, as the water would be way too shallow. You can even see that the water level only goes up to the Sentinel's ankle area when it is standing upright in the ocean. (00:03:15)
Other mistake: When Batman is watching the security footage of Victor Fries' accident, at first Fries is addressing the camera directly which follows him and pans according to his movements and Ferris Boyle interrupting him, which would suggest a second person was in the room with a handheld camera. But after Ferris Boyle enters the room and orders Fries' experiment terminated, there are several cuts from various angles in the room suggesting surveillance cameras. The surveillance style footage also often conveniently cuts to the face of whichever person happens to be speaking or will cut to a certain angle in order to put emphasis on the action, all of which would require multiple mounted cameras and purposeful editing by either Boyle or one of his subordinates, which would be completely illogical since they don't want anyone to see the footage in the first place. (00:12:20 - 00:13:55)
Continuity mistake: In the 1991 flashback, Jamie is already engaged to Paul and is shown with long hair. However, in the 'Cold Feet' episode, Jamie is shown with short hair. Since the 'Cold Feet' episode was set in February of '91 and the flashback from this episode was set in late March or April of '91, these two episodes don't match up.
Continuity mistake: When the immortal who's trying to kill Tessa snipes at her in Duncan's car, his shot shatters the passenger-side window. When Duncan tails Tessa and her police escort to the safehouse, the passenger-side window is intact. (00:30:05 - 00:35:50)
Factual error: In many episodes, cars which are said to be owned by a character have a Certificate of Fitness on their windscreen. Private passenger vehicles in New Zealand under 3.5 tonnes have a Warrant of Fitness, not a Certificate of Fitness. This means these cars are most likely rentals.
Revealing mistake: At the beginning of the episode, Hank is re-watching Larry's announcement that he won't be renewing his contract after this season. The video tape that he is watching is sticking out of the VCR, which means it's been ejected and can't be playing. His assistant then comes in and says "This again? I'm taking this tape away from you," and removes it, so we know it wasn't on air or from a different source. (00:00:25)
Character mistake: Near the beginning as the leader is about to set off with the boys, he says, "About face!" and turns to the left, and the boys follow suit. But "About face" means to turn 180°. He should have said "Left face" to get them to turn 90° to the left. (00:04:25)