Continuity mistake: When Buffy receives her letter from UC Sunnydale it says her address is 1630 Crestview, this doesn't sync up continuity-wise with the episode The Body as she tells the 911 operator that her address is 1630 Revello. She didn't move so it's a definite mistake.
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Continuity mistake: When we see Xander and Anya going over the seating arrangements for their wedding, Xander is eating from a large sack of crisps. During the conversation Anya takes them off him, he takes them back and places the bag next to him. We see the bag after Xander puts it down, and in a closeup shot of him, the front of the bag is facing upwards. But when Dawn comes in, the front of the bag is facing downwards - barcode and ingredients are visible.
Continuity mistake: At the beginning of the episode when Buffy offers Dawn another burger from Doublemeat Palace, she is holding the burger in her hands just before Willow comes in with her line, "Hey, workin' lady. Rough night?" The burger then jumps from the kitchen counter to Buffy's hands between shots.