Plot hole: In the episode where Jessica went home to her family's house in season 2, Bill said "someone who lives here must invite me in." In this episode, Russell Edgington's wolf (Coota) invites Russell into Alcide's apartment. Also, in Season 6 Sarah Newlin recinds Jessica's invitation into Jason's house (which only Jason should be able to do).
Other mistake: The battle droids - including the commando droids featured here - habitually have two broad fingers and a thumb. So how can a commando droid squeeze itself completely into clone trooper armor without its broad fingers tearing open the gloves, since it can't separate its fingers?
Continuity mistake: All shots of the Jeep Cherokee prior to it crashing (and during the process of flipping over) show that it wears factory-optional silver steel wheels of a 'star' style. But as the wreck settles upside-down, it's wearing plain steel wheels (like those found under full wheel covers or on a spare tire).
Factual error: In the show Gaius wears glasses, except eyeglasses first came into use in the late 13th century while the legend of King Arthur is around the 5th or 6th century.
Triumvirate of Terror! - S3-E8
Continuity mistake: After Joker subdues the other Amazonians, he is disguised as a female warrior and talks to Wonder Woman and her mother. There are no Amazonians knocked out in front of Joker and one is beside him with her head behind him. But in the reverse angle, that one has vanished and there is suddenly another Amazonian adjacent in front of Joker with her body in a different position. (00:11:10)
Continuity mistake: Season: 1, episode: 16 "Bloodline". As two soldiers of Darken Rahl approach the plains of Morrow, they break a magical shield which catches them on fire. Two frightened soldiers run away, and the commander shoots one. Keep an eye on the commander - he is still pointing the crossbow even after the soldier dies. The next shot, however, has his crossbow loaded with another arrow, daring anyone else to run away.
Revealing mistake: In the scene where Mitchell first visits McNair's van, Mitchell's reflection is visible in the window on the left side of the screen during the shot where he first opens the van door. The vampire lore of the show informs the viewer many, many times that vampires (such as Mitchell) and ghosts cannot be seen in reflections, pictures, or videos (their image "cannot be captured"). The reflection can be seen for roughly 20 seconds. (00:23:20)