Continuity mistake: When the Buffybot is at the parent teacher day and she is looking at the student model of a Utopian city, the hover cars are moving around the model on a wire. But when the shot changes, the cars aren't moving. Then in the next shot, they're moving again.
Revelations - S3-E7
Revealing mistake: When Gwendolyn Post fights Angel in the mansion, she breaks a long-handled shovel over her knee to create a stake. If you watch in slow motion, the handle of the shovel is pre-broken (she simply holds the two pieces together tightly), and the pieces separate just before they actually make contact with her knee. (00:34:55)
Continuity mistake: At the end of the episode, as Spike's getting his T-shirt on, from one angle he gets his arm completely through a sleeve, then we cut to a different view and he's still pulling it on.
Continuity mistake: When Buffy opened the trunk for the first time, the corpse of the real Ampata is lying with its head to the right of the trunk. When she opens it the second time, the corpse is lying with its head on the other side.
I Only Have Eyes For You - S2-E19
Continuity mistake: When Buffy is waiting in Principal Snyder's office, the 1955 year book slides off the bookshelf and lands open, but when Buffy walks over to pick it up, the book is closed.
Continuity mistake: When Joyce is being interviewed by the policemen at the house, you can see the number outside the house, but it says 163 instead of 1630, the number on which Buffy lives.
Lover's Walk - S3-E8
Continuity mistake: In the scene when Spike was in Buffy's kitchen with Joyce, Buffy keeps him down on the table and grips Spike by the throat. She uses her left hand (in the close shot it is also the left hand) but in the next scene when Angel is also in the kitchen and Spike hits Buffy's hand, she uses her right hand (Spike hits her right hand).
Continuity mistake: In the previous episode, Empty Places, Kennedy had a cut across her nose and two more between her eyebrows in the last scene. In the first scene of this episode, which takes place a few minutes later, the cuts are completely gone.
Visible crew/equipment: In the last scene after Buffy jumps through the window into her mother's room, Faith and Buffy begin to fight. The two wrestle into the hall and begin to roll down the stairs. There is a side view shot then a front view shot. In the front view shot you can see a camera moving downward just outside the bannister and out of shot. Only visible in widescreen versions.
Some Assembly Required - S2-E2
Other mistake: In all episodes where the high school football team is mentioned, they are called the RAZORBACKS but in this episode the cheerleaders cheer for the GREENBACKS (it wouldn't even make sense if this was a nickname as SHS colours are yellow and burgandy).
Continuity mistake: In Innocence, when the Scoobies are in the library, Oz (I think) says for the crew to meet outside Xander's house a half hour later. Then we cut to Buffy strolling through Sunnydale High in broad daylight, then back to Oz's van outside the military base and it's last night again. (00:23:15 - 00:29:20)
Audio problem: While Faith is stabbing the demon in his apartment, we hear the sound of her knife going through, and him yelling in pain. However, the last sound of her stabbing him comes a little late: The knife isn't even touching him.
Continuity mistake: When Xander falls through the ground, he lands with his arm on, or very near a bit of wood, but in a closer shot of him just before he gets up, the wood's disappeared and other rubble has moved around too.
Checkpoint - S5-E12
Continuity mistake: In the series 5 episode 'Checkpoint' when Buffy has just accidently axed the dummy, watch her blindfold. It goes from being pushed up above her forehead on her hair, to being right down by her eyes. This changes between every shot. (00:27:55)
School Hard - S2-E3
Continuity mistake: When the Anointed One is killed by Spike, he disintegrates into dust. But in the overhead shot, there is no dust on the floor, even though it should have fallen through the bottom bars of the cage.
Continuity mistake: In the scene where Buffy and Kathy are deliberately infuriating each other (tapping pencils and cracking eggs) there are several lights on throughout the room (on Buffy's desk, above Kathy's computer, in the kitchenette) yet when Buffy turns out her bedside lamp, the entire area is thrown into darkness.
Audio problem: When Joyce is about to leave for the pre-show, we hear Xander say "Have fun, but not too much fun", but his lips never move.
Continuity mistake: In the library, a book in front of Buffy begins to slide off of a stack of books. Change of camera and book is back on top of stack.
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.