Continuity mistake: After Buffy finds Morgan's brain, Willow pulls up Morgan's school file on one of the library computers without even touching the keyboard. One moment the monitor is on the desktop, the next it's showing Morgan's file.
Continuity mistake: When Giles walks up to Buffy, Xander and Willow after The Body is found at the beginning of the episodes, watch the extras walking by in the background. They don't always match as the shot cuts back and forth between Giles and Buffy/Xander/Willow. Ex. When Buffy asks "Vampire?" nobody is walking behind her, but when it cuts to the opposite angle, suddenly two students are walking by from Buffy's direction that weren't there before. This sort of thing happens at least two or three times.
Continuity mistake: After the credits, when Buffy, Xander and Willow sit down to talk about what to do for the talent show, two people walk into the background behind Buffy and are standing there talking throughout the scene. At one point, it cuts to Xander for about one second when he says the line "Whatever happened to corporal punishment?", then cuts back to Buffy, and the two people behind her are suddenly gone. There's not enough time for them to have walked away between shots - they simply vanish.
Continuity mistake: When Snyder grabs Buffy after she breaks into the locker, when she turns around, he is holding her hand up by the wrist. The height he is holding her hand up changes a few times between shots. Sometimes it's up by her face, other times it's level with her neck, at one point it's down by her shoulder, etc. Obviously snippets of a few different takes were used, and he wasn't holding it up at exactly the same height each time.
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.