Audio problem: When everyone is in the Bronze - just before the vamps show up - you hear the first line of a song being played, Ballad For Dead Friends by Dashboard Prophets, cut to outside and you see the vamps strolling along and killing the doorman, then cut back into the Bronze and the same line plays again. This is a total error in cutting the show, it is stated there is no live band but still the same line plays twice when that is not how the song goes.
Audio problem: When Xander, Willow and Ampata meet up at The Bronze, the song the band is playing is at the point of a guitar solo. If you watch Oz (who has already been established as 'lead guitarist') on stage in the background; he's blatantly NOT playing that solo. The hand movements don't match up.
Audio problem: When Giles and Anya are talking to the demon, trying to get him to open the portal to Beljoxa's Eye, when you see Anya's face from the side, her lips don't sync up with what she is saying, and sometimes her lips are moving to words when she doesn't have any lines at all.
Audio problem: When Buffy has just killed the Suvolte demon and Riley is found out to have not told her it was a tracking only mission Sam says something like 'If we weren't under time constraints, I'd rip you a new one.' Riley then says 'Stand down soldier.' Buffy asks Sam, 'Is he your boss?' And Sam replies 'He wishes. We better regroup.' But her lips to not move when she says they have to regroup. You can see her mouth on screen and she is just smiling, not moving her lips at all.
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.