Nightmares - S1-E10
Continuity mistake: At the beginning of the episode when Buffy and Willow stop at Buffy's locker, in the first shot, Willow has her backpack strap on her shoulder and takes it off. It then cuts to another angle and Willow's backpack strap is back on her shoulder, and she takes it off a second time.
Nightmares - S1-E10
Continuity mistake: In the beginning dream sequence, when Buffy is surprised by the Master and backs up into the wall, watch her two pigtails. As the scene cuts back and forth between Buffy and the Master, her pigtails move from behind her shoulders to in front of her shoulders and back several times. First they're both behind her shoulders, then only one is behind, then both are in front, then one moves back behind again, etc. Obviously multiple different takes were cut together in editing.
Nightmares - S1-E10
Continuity mistake: Buffy's history teacher is not the same person from episode 1 or 9, originally a woman, the teacher is now a man. Cordelia also notes Buffy doesn't know where the class is due to ditching, but we saw Buffy in her history class with Cordelia in The Puppet Show. How could Buffy not know where her class is only 1-2 weeks later?
Chosen answer: Angel is saying that he is still jealous and Buffy recognizes that this is his way of saying he wishes that they could be together. That is why they both smile.