Deliberate mistake: Every time the commandos are seen in the early episodes of this season (The Freshman and Fear, Itself) they wear ski masks to protect their identities. Starting in The Initiative, they stop doing this. The reason is that the audience needs to be able to identify the different commando characters, but it's still a discontinuity.
Buffy The Vampire Slayer (1997)
1 deliberate mistake in season 4 - chronological order
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)
[After saving Giles from a vampire.]
Spike: Awww, poor Watcher. Did your life flash before your eyes? Cup of tea, cup of tea, almost-got-shagged, cup of tea?
The Freshman - S4-E1
Trivia: At the Bronze, Buffy sees someone whom she thinks is Angel. Until his face becomes visible, revealing it's someone else, the man she sees is played by David Boreanaz.
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.