Revealing mistake: The entire scene where Buffy is experiencing accelerated time, shadows of trees move in the wind but never actually grow or shrink. Even over short increments of time, the sun can move shadows noticeably, and judging from the speed of the people around her, Buffy is in accelerated time for at least half an hour. (00:08:25)Phoenix
Revealing mistake: As Willow walks through the forest pursuing Warren, just after we first see Warren running, there's a shot of Willow walking into a bit of a clearing. Her shadow crosses a tree on the right (could be caused by the moon), but then a couple of seconds later another shadow is visible on a tree to the left - obviously an artificially lit forest. (00:33:15)Jon Sandys
Continuity mistake: Where Willow is pulling the bricks out of the jail near the beginning of the episode. When she first pulls the bricks out of the arch thing they are from a different area than when you see the arch from the inside of the jail, even allowing it to be 'inside out' (as seen from outside and then the inside).
Continuity mistake: In the episode (series six) where Buffy thinks she killed Warren's ex-girlfriend, when she's at the police station, in the over the shoulder shot of Desk Sergeant, he is holding the phone between his shoulder and ear. But in the front shot of him the phone has jumped to his hand. (00:36:45)