Plot hole: When Buffy talks to Xander at the end and he tells her to stay with Riley, she mentions that he is going at midnight. But earlier in the episode, Riley doesn't tell Buffy he is going at midnight, he says "Transport's leaving tonight" first, and at the end of the conversation he says "Unless you give me a reason to stay, I'm leaving tonight". Nowhere in this episode does he tell Buffy that he's leaving at midnight.
Continuity mistake: When the gang are fighting Glory's minions, one of them knocks Giles to the ground and then tries to choke him. As Giles hits the ground he lands facing downwards so we can't see his face. But when the minion is chocking him in the shot immediately afterward, he is suddenly facing upwards.THGhost