Other mistake: We're shown a variety of photographs and pictures of different members of the gang at one point. One of those, the one of Xander and Anya, is actually a shot from the episode "Something Blue". I doubt very much that during the events in that episode, someone conveniently decided to take a photograph.
Buffy The Vampire Slayer (1997)
1 other mistake in Same Time, Same Place
Continuity mistake: Willow is turned into a ghost. Throughout the entire episode, she can't touch anything (can't turn the pages of a book, etc.), yet towards the end when she and Giles go to Ethan's shop, and she leaves, you can hear that she opened and closed the door, even though she can walk through walls and can't actually touch the door. The curtain moves when she leaves too. (00:34:05)
School Hard - S2-E3
Vampire: And when I kill her, it will be the greatest event since the crucifixion. And I should know, I was there.
Spike: You were there?! If every vampire who said he was actually at the crucifixion really was there, it would've been like Woodstock!
Once More, With Feeling - S6-E7
Trivia: In 'Once More, With Feeling' the man singing the mustard song is David Fury, the co-executive producer.
Question: At the last moment before leaving for good, Angel pauses to tell Buffy "I don't like him" [Riley], to which she replies with a large smile "Thank you." Why does she take this comment surprisingly well? From an ex boyfriend to her new boyfriend? It's not like it sounds like a friendly warning of any sort, nor a joke given the tense situation between the two guys in the episode. And the smile on Buffy's face does not make her response look ironic either, more like loving/caring. Is that a cross over reference to another dialogue in the Angel series?
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.