Continuity mistake: In "Becoming Part 2" At the end when Spike chokes Drusilla unconscious, he picks her up, one of her hands is resting on her stomach and the other is hanging to her side. It cuts to a shot of Spike looking at Angel and Buffy fighting then to Spike leaving with his back facing the camera. You can see that the hand resting on Drusilla's stomach moved to Spike's shoulder.
Continuity mistake: When Glory challenges Dawn to name one person who can cope with life on earth, there is a close up of Dawn answering "Buffy". In this shot, the black mark (where she has been annointed) that is there before and after, has completely disappeared.
Continuity mistake: When Buffy is singing "Something to Sing About", she sings the verse beginning 'All the joy life sends, family and friends', and we see that Anya and Tara are stood in the background, about 3 metres apart from each other. However, for one shot, they appear less than 1 metre from each other.
Plot hole: Giles tells Willow to leave him while he extracts information from Ethan on how to break the costume spell. By the time Giles smashes the statue Willow has already found the others, who had left the house where she thought they were and are hiding in a completely different area of the town. No matter how long it took Giles to beat the information out of Ethan, there is no way Willow could have gotten back to the house, realised they were gone and tracked them down before the spell was broken. As a ghost, it is possible she could have happened across them even though they were hiding, but seems unlikely.
Continuity mistake: In Graduation Day Part 1, when Faith and Buffy are fighting, Faith throws Buffy into the wall near the TV, but the TV is intact. A few shots later, there is debris on the floor, glass and such, from the TV, and when it's shown again, the TV is unbroken. This happens a few times. In Graduation Day Part 2, when Faith and Buffy are talking in the apartment, the TV is broken again.
Continuity mistake: In the season two episode, 'When she was bad', in the scene where Buffy smashes the masters skeleton with a sledge-hammer she smashes the rib cage to pieces. Suddenly the rib cage has again become completely intact and she smashes it to hell again.
Audio problem: Near the end of the episode when Giles, Tara, Faith/Buffy and Willow arrive at the church and a police officer tries to stop them going inside Willow says, 'Oh no you don't understand (or words to that effect) but her mouth doesn't move at all, it was clearly dubbed.
Continuity mistake: After Buffy slams the Gavrok spider thing on the ground with her back, she gets pulled up by Angel. We see this shot from the back, and we see that the Gavrok is no longer on the floor or on her jacket. In the very next shot, we see Angel kick it across the floor. Where did it come from?
Revealing mistake: In the scene where Giles and Ethan Rayne are drinking in the bar, the shots cut between Giles and Ethan frequently. When on Giles, you can see Ethan's hands/arms and his glass in the foreground of the shot, but almost every time the shot switches back to Ethan he's in a different position with no time to have moved.
Visible crew/equipment: In the last scene after Buffy jumps through the window into her mother's room, Faith and Buffy begin to fight. The two wrestle into the hall and begin to roll down the stairs. There is a side view shot then a front view shot. In the front view shot you can see a camera moving downward just outside the bannister and out of shot. Only visible in widescreen versions.