Audio problem: When Joyce is about to leave for the pre-show, we hear Xander say "Have fun, but not too much fun", but his lips never move.
Audio problem: When Joyce comes downstairs and comments on the breakfast Buffy made, Dawn says 'Oh, Buffy helped,' but her mouth doesn't match what she's saying.
Audio problem: At the start of the episode when Buffy and Dawn are with Joyce in the hospital room, Dawn starts eating jelly, and when Joyce starts speaking you can see in the left hand corner of the screen Dawn talking, but no words are coming out.
I Was Made To Love You - S5-E15
Audio problem: When Spike arrives at the magic shop with a burning blanket over his head, he throws it to the ground and stomps on it, yelling, "Fire! Fire!" As he yells "Fire! Fire!" however, his lips aren't moving.
Chosen answer: He had larangitis and because of the shooting specifications they had to have him shoot the scene with a bad throat, they then re-recorded his lines and dubbed them. At various points during the scene and indeed the episode you can see him touch his throat or rub it.