Other mistake: In episode "Helpless" in season 3, after the council member bitten by the crazy vampire rises, his bite marks heal. But in season 7's "Lies My Parents Told Me," it shows Spike's mother already risen and her bite marks are still there.
Never Kill A Boy On The First Date - S1-E5
Other mistake: In the famous scene where Buffy tells Giles, "If the Apocalypse comes, beep me," she grabs her pager from out of shot. Trouble is, she's standing in the middle of her hall and there's nowhere she could have picked the gadget up from. (00:21:00)
Other mistake: Willow's computer beeps twice when her first email from Malcolm is received through before she is kidnapped by Fritz, but only beeps once when the second email is received.
Other mistake: When Sid gets into Buffy's bed and Buffy screams, her mum immediately comes into her room to find out what's wrong. Now, unless she sleeps on the landing, Buffy's mum is really quick at getting out of bed.
Other mistake: In the very first shot (a long tracking shot backstage), watch the girl practising with her tuba. At one point she pulls her mouth away and then leans back in and starts playing some notes. But you can tell that she isn't blowing into it, and in fact, her mouth isn't even quite touching it. So it shouldn't be producing any notes. Then, almost immediately after, you can also see the actress purposely moving the tuba (sort-of rotating it to her right) to get out of the cameraman's way.
Other mistake: The Master's skeleton, before it is destroyed, looks to be female and not male. (Note the wide hips and large birth canal-like hole.) Also in the Next season's "When She Was Bad," they have another shot of the same skeleton, however the hips are much smaller and more male. (00:43:55)
Other mistake: At the end of the episode Willow mentions going to the Bronze on a Wednesday night, Buffy also mentions to Giles that she got almost everyone killed on the second day of school. From the different clothing being worn each day, it's obviously been more than 2 school days and should instead be Thursday by the end of the episode.
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).
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.
Other mistake: When Buffy and Angel escape from Spike, Dru and the Judge they jump down into the sewer, then run all of five metres before going up the ladder to escape. When they come out of the sewer they are in a very open area with the factory nowhere in sight. They have not travelled far enough for this to be the case. (00:39:15)
Other mistake: When Angel, Drusilla and The Judge enter the mall, The Judge kills a pedestrian as he tries to get away. But no other pedestrians that are in the mall notice - A big blue guy just set a man on fire and disintegrated him into tiny pieces in a public mall and NOBODY noticed?
Bewitched, Bothered And Bewildered - S2-E16
Other mistake: Joyce tells Cordelia to grab some bandages for Xander from the bathroom upstairs. Joyce and Xander are in the kitchen and there is a small corridor that leads to the stairs, but Cordelia goes around the other way leading to the living room. Fair enough, Cordelia made a mistake. She isn't that bright. But she returns with the bandages coming back from the living room. Why come downstairs and then go All The Way around through the living room when she could have just walked down the small corridor?
Other mistake: In the basement when Death throws Ryan to the floor, Ryan lands pretty softly considering that he was just thrown pretty hard.
Other mistake: Buffy freaks out when she's first taken to the hospital. Joyce tells the gang it was because her cousin died when they were young, but in season one episode "Angel" Buffy has no problem being in the hospital, same with later seasons.
Other mistake: After Gage turns into a monster and fights Buffy, the two monsters slide into an open grate. During the shot, there's some sort of weird "glitch" in the background where the garbage can and wall seem to slightly move. All I can assume is that a few frames were trimmed to speed up the shot and it may have exaggerated subtle camera movement, making the background appear to "jump" slightly.
Other mistake: At the beginning of the episode when Giles visits the archaeologists who have obtained the obelisk, it appears to be much too tall/wide to have fit through the door.
Other mistake: When Willow is attempting the spell in the hospital, the subtitles state that Xander is speaking a line of the incantation. It is actually Oz speaking - Xander is off rescuing Giles, as we see in the very next shot.
Other mistake: In the episode 'Anne' Kenn tells Buffy that time in his hell dimension passes more quickly, that one day on Earth is the same as 100 years in his dimension. This means time goes roughly 36,000 times quicker. When Lily falls into the portal, it's at least 10 seconds until Buffy jumps in after her, but Lily is still just sitting there looking stunned. If times moves that much faster, 10 seconds would become over 4 days. Would Lily still have been just sitting there?
Other mistake: When Angel fights with Buffy in the forest you can see that he hasn't got shoes on, just socks. Later, when Buffy goes back to the mansion and Angel is chained up, he's wearing shoes. How did he manage to put them on, if he was in chains?
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.