Continuity mistake: In the alleyway scene after the real Buffy kills all the Hellions (biker demons) and runs off, one of the Hellions can be seen getting up behind Xander. We then see a closeup shot of the Hellion opening its eyes while still lying on the ground and then they stand up and sneak up behind Xander again.
Continuity mistake: When Spike is looking out the window at the demons rampaging in the street outside Buffy's house, Dawn can be standing behind him with her hair trailing down below her breasts. In the next shot, when Spike pulls her away from the window, her hair is pulled back behind her shoulders despite her not having moved.
Visible crew/equipment: When Buffy and Dawn are at the top of the metal tower, and Buffy is still very dazed from being called back, there is an overhead shot with a piece of the tower falling down; if you look left of the falling piece, you can see a guy wearing a hard hat walking about.