Welcome To The Hellmouth (1) - S1-E1
Continuity mistake: This is hard to describe. When Buffy and Joyce are talking in her room, Joyce keeps pulling pillows off Buffy's bed and re-arranging them. However, at one point, when the shot cuts back to her, she's holding a different pillow than in her last shot. This technically wouldn't be a mistake since she's off camera except in the shots facing Buffy, there's a mirror behind her with her bed in view, so we should have Joyce put down the first pillow and pick up the second one... and we don't.
Continuity mistake: Right as Buffy gets out of the car and watches Joyce drive away, Cordelia and her friend are walking up the stairs, along with a girl in a blue shirt at the top of the stairs walking towards the school. The next shot Buffy is walking towards the stairs, Cordelia is already far away chatting with her friend and the girl is blue is back on the stairs again. (00:27:00)
Out Of Mind, Out Of Sight - S1-E11
Continuity mistake: When Cordelia is giving her May Queen speech, Willow notices 2 body guards standing around. In both shots you can see the same 2 girls, wearing light blue and grey, walk behind The Body guards. The same girl in light blue can also be seen in several different shots, in the crowd listening to Cordelia and walking around as Buffy talks to Willow and Xander.
Continuity mistake: A cut scene shows the sun had just gone down right before Buffy heads to the Bronze and Joyce tells Buffy she will make them dinner if she chooses to come downstairs. This would assume it is evening. When Buffy kills Luke she says sunrise is in 9 hours. Considering this episode takes place in March, that would mean the sun would have gone down around 7pm. But 9 hours from sunrise would be around 10pm.
Continuity mistake: When Buffy is shown pulling the secret chest out of her closet with weapons against the vampires, the window behind her shows daylight, but when she steps out of her window it is fully dark. There is also a cut scene right before that shows it was twilight, but there was late afternoon sunlight shining through the windows of her room. It's not possible for the sun to go down that fast.
Continuity mistake: In many historical flashbacks, most notably Spike's and Anya's, hair and wigs differ greatly from previous flashbacks or episodes. The director even discusses it during the commentary on Lies My Parents Told Me, saying that he doesn't understand why the wigs aren't consistent.
Blood Ties - S5-E13
Continuity mistake: In the first scene of the episode, just after the teaser, the Scoobies are gathered around the table at Giles' magic shop. During the second part of the scene, we can see Anya is alternatively lying her arms under or above the table depending on the camera angle, whether from behind or facing her. (00:01:55 - 00:03:15)
Continuity mistake: When Spike is stalking Buffy in front of her house, she somehow senses him and pulls him out of behind the tree in front of her porch. While he is being pulled out, he has no cigarette in his mouth. However in the next close-up shot, he has one (which he then quickly throws away). (00:29:55)
Continuity mistake: When Xander is shot by the demon's lightning rod, he falls on a heap of black trash bags. When he is helped to stand up, different bags, pink and white ones, are visible instead. (00:11:30)
Continuity mistake: When the group is debriefing about their first Dracula encounter at Giles', Anya is sitting on the sofa with her hands crossed on her lap. In the next shot she has her arms straight with the palms of her hands on the sofa cushion, fingers towards the back. (00:11:25)
The Freshman - S4-E1
Continuity mistake: When Buffy is talking to Giles after his run, his towel moves from being on one shoulder to being across his back and over the other shoulder to being back on one shoulder.
Continuity mistake: Near the end, when Spike takes the cup of blood from the fridge, we can see that it is full to within a 1/4 inch of the rim. However, when the shot changes and he drinks it, he tips the cup almost 45 degrees before putting his lips to the cup and drinking. If the cup had been as full as previously shown, the blood would have begun pouring out long before Spike ever drank form it.
Band Candy - S3-E6
Continuity mistake: The tattoo on Giles' arm is reversed compared to the way it was facing in the "Dark Age" in season 2.
Continuity mistake: After drinking the water with the virus, Buffy looks into a room and her hair is damp and brushed back. In the next shot, it's dry and parted down the middle.
Continuity mistake: Anya's hair changes from straight in the previous episode to curled in this one, even though it is set directly after.
Nightmares - S1-E10
Continuity mistake: Buffy's history teacher is not the same person from episode 1 or 9, originally a woman, the teacher is now a man. Cordelia also notes Buffy doesn't know where the class is due to ditching, but we saw Buffy in her history class with Cordelia in The Puppet Show. How could Buffy not know where her class is only 1-2 weeks later?
Continuity mistake: In the end of the scene where they find the dead mental patient killed by the meteor alien, the group walk away from The Body leaving Riley still there, but Anya's coat can be seen in the bottom left corner after she had walked away.
Continuity mistake: After Riley stakes Spike and Spike decides to drink, he is shown opening the bottle. The camera shows Riley and then goes back to Spike. Spike is holding the bottle, lid still on, then he goes to open it again.
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.