Continuity mistake: During Anya's pep talk to the Potentials, Andrew draws crude illustrations to visualize what she is saying. One the second page that uses to draw a picture of the sun, the top of the previous page that's folded over the back of the board changes from being folded straight to folded at an angle between shots.
Continuity mistake: In the episode 'Empty Places' when Xander is returning from hospital Kennedy is standing beside the couch to greet him and Willow. When Xander sits down she is sitting on the couch, but she wasn't out of shot long enough to have gotten there.
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.