Continuity mistake: When Riley is dressing Buffy's wound, it is much further to her left side than where she was actually staked, which was more central on her stomach. (00:00:35 - 00:02:40)
Visible crew/equipment: When Spike picks up the money after Buffy has just said "you're beneath me", you can see the microphone "sender" under his leather jacket. (00:36:10)
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.