Continuity mistake: When Buffy fights the guards and says, "Anyone who isn't having any fun here follow me," the top under her jacket is purple. In the next shot, when she turns to walk out, it is green, then back to purple when we see her again.
Continuity mistake: When Xander is showing Willow and Buffy his fake ID and the view of the shot is from behind Xander, he is holding the card with his thumb and middle finger. Switch to the view from behind Willow and it's being held with his thumb and index finger. Then it switches to behind Xander again and it's back to thumb and middle finger.
Continuity mistake: Towards the end, when Buffy stops the arrow, when she first grabs it her hand drops down to Cassie's mouth level, and her arm's bent at the elbow. When we cut to another angle it's now held at arm's length and at about eye level.
Continuity mistake: When Joyce is talking to Buffy about the shadow, after she says "sometimes weeks", she turns towards Buffy. In the next shot she's facing away from her, then turns to face her again. (00:10:55)
Continuity mistake: In the basement scene, with Jack and Xander, the bomb counts down from 13 to 10 seconds. Then after Xander says his line, the bomb again shows 13 seconds.
Once More, With Feeling - S6-E7
Revealing mistake: During the song-and-dance number "They Got The Mustard Out", if you look closely at the dancers, the man in green to camera right of the second row is horribly out of step with the music, and with the rest of the group. The spell makes everyone dance far better than they naturally would (Tara loses the clumsiness she often displays, for example), so it is a mistake to have someone under the spell dancing so badly.
Continuity mistake: In "Becoming Part 2" At the end when Spike chokes Drusilla unconscious, he picks her up, one of her hands is resting on her stomach and the other is hanging to her side. It cuts to a shot of Spike looking at Angel and Buffy fighting then to Spike leaving with his back facing the camera. You can see that the hand resting on Drusilla's stomach moved to Spike's shoulder.
Once More, With Feeling - S6-E7
Continuity mistake: During "Something to Sing About, when Buffy sings, "You don't get to rehearse," Tara walks past the support pole behind her. In the next shot from an angle, she's closer to the middle of the room and the pole is not visible. (00:41:40)
Continuity mistake: When Buffy puts her egg down, the position of the chain and pen she sets it down by change depending on whether the shot's from Willow's side or Buffy's. (00:08:40)
Audio problem: When Anya comes in from helping the potentials get in the car, she says that Molly is in the trunk. She then says something along the lines of "I'm surprised at how compact Molly is," as she walks away with Willow, but her mouth doesn't move.
The Weight Of The World - S5-E21
Continuity mistake: When Glory challenges Dawn to name one person who can cope with life on earth, there is a close up of Dawn answering "Buffy". In this shot, the black mark (where she has been annointed) that is there before and after, has completely disappeared. (00:24:05)
Once More, With Feeling - S6-E7
Continuity mistake: When Buffy is singing "Something to Sing About", she sings the verse beginning 'All the joy life sends, family and friends', and we see that Anya and Tara are stood in the background, about 3 metres apart from each other. However, for one shot, they appear less than 1 metre from each other. (00:42:05)
Revealing mistake: In the last episode, 'Chosen', Anya beheads two Ubervamps. The second time she swings the sword it very noticably doesn't go anywhere near the Ubervamp's neck, closer to its stomach.
Revealing mistake: As Willow, Cordy, Miss. Calendar and Giles are wheeled over the bones of the Master, Giles goes past and his hand brushes against the bones - the skeleton bends, revealing that it is rubber. (00:36:10)
Revealing mistake: Although the mirror in Buffy's room is mostly covered by photos, Angel's reflection can be seen for a split second as he walks past it to pick up the photo of Buffy ice-skating.
Continuity mistake: In Graduation Day Part 1, when Faith and Buffy are fighting, Faith throws Buffy into the wall near the TV, but the TV is intact. A few shots later, there is debris on the floor, glass and such, from the TV, and when it's shown again, the TV is unbroken. This happens a few times. In Graduation Day Part 2, when Faith and Buffy are talking in the apartment, the TV is broken again. (00:38:05)
School Hard - S2-E3
Other mistake: As Spike is walking down the hall, you can see a reflection of his head on a locker to his left.
Visible crew/equipment: In the final scene in the Magic Box where Buffy cries, in several shots of Buffy you can see, in the right of the shot, the sleeve of a white shirt, which none of the characters are wearing.
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.