Continuity mistake: At the Bronze in the beginning of the episode, two guys are talking about girls. At one point, one of them (the white guy) goes from facing forward to facing sideways at his friend between edits.
Audio problem: After the opening credits, we see a band playing in the Bronze. The lead singer's mouth doesn't seem to 100% match what he's saying. It's mostly right, but just seems a little "off." (Ex. There's a few very brief moments where individual syllables seem to not match, etc.) It's very clear he's simply lip-syncing to a pre-recorded track.
Continuity mistake: In the beginning of the episode, when Buffy's teacher is looking at the slides, he goes from holding a slide with one hand to two hands instantly between edits.
Continuity mistake: In the beginning of the episode, Buffy's teacher turns on a light box and places a single slide on it. In the next shot, you can see the light box reflected in his eyeglasses, and in the reflection, you can see there are suddenly four or five slides on the light box. Then in the very next shot, there are suddenly NO SLIDES WHATSOEVER on the light box, and he places two down.
Continuity mistake: In the opening scene, the vampire makes Buffy back up into a pillar. In the first shot, Buffy is only inches away from the pillar. The camera cuts to the vampire for a second, then when it cuts back to Buffy, she's suddenly moved forward several feet and backs up into the pillar finally.
Continuity mistake: In the opening scene, when you first see the vampire, you see a girl behind him running from screen-right to screen-left. She's in a blue plaid shirt and jeans. The scene cuts to Buffy for a second, then cuts back to the vampire and you can see the same girl doing the exact same thing in the background... running from screen-right to screen-left. (It looks like they used two different takes of the same shot in the scene).
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)
Never Kill A Boy On The First Date - S1-E5
Continuity mistake: When Buffy is talking to Owen at the end, there is a woman wearing a red/black checkered jacket, sometimes carrying a red bag, walking up the stairs behind Owen several times. You can also see her behind Buffy in shots facing her. (00:40:25)
Never Kill A Boy On The First Date - S1-E5
Continuity mistake: When the vampire breaks the glass with his head, the remaining glass disappears.
Never Kill A Boy On The First Date - S1-E5
Continuity mistake: When the Scoobys are in the cafeteria in the beginning, Xander asks what the "green stuff" is in a wideshot, and it cuts to a closeup of Buffy. In both shots, you can see two extras in the background doing the exact same thing twice - walking from screen-left to screen-right, while one of them distinctly lifts their tray up for a moment. The extras were probably just told to repeat the same actions in different takes to populate the background, leading to this odd mistake.
Never Kill A Boy On The First Date - S1-E5
Continuity mistake: When Borba reawakens at the funeral home and says "I have been judged, " you can sort-of see Owen reflected in the glass in front of him, and Owen's face looks totally blank. When it cuts to Owen, Xander and Willow (right before the commercial break happens), Owen suddenly has a shocked expression on his face.
Never Kill A Boy On The First Date - S1-E5
Deliberate mistake: When Buffy and Giles are searching the funeral home, we see three shots of Buffy and Giles opening up different mortuary-cabinet doors, shot from the point of view of the cabinet. The problem? You can tell they're opening and closing the same door over and over again. The background is exactly the same, and all they've done is slightly re-arrange the stuff behind them, and had the actors come in from different angles to create the illusion they're opening different doors. It's SUPER obvious.
Never Kill A Boy On The First Date - S1-E5
Continuity mistake: When Buffy introduces Owen to Angel, Buffy starts to scoot towards Owen but is still a good foot away. However, when the shot cuts, suddenly she is pressed right up against him.
Never Kill A Boy On The First Date - S1-E5
Continuity mistake: During Buffy and Owen's date at the Bronze, after Buffy shoos away Cordy, Buffy turns and smiles at Owen. In the first shot, she's smiling with a closed mouth. Suddenly in the next shot, she's open-mouth grinning with her teeth exposed.
Never Kill A Boy On The First Date - S1-E5
Continuity mistake: After the crash, when the bus driver walks up to the vampire that he hit and asks "Can you move?" the blood that was on the right side of his forehead in the previous few shots vanishes.
Never Kill A Boy On The First Date - S1-E5
Continuity mistake: The second time we see the van going to Sunnydale, the creepy guy is delivering a weird sermon. At one point, we see him reflected in the driver's mirror, and he is gesturing with his right hand, which is up around his abdomen/chest area. It then cuts and suddenly his hand is down by his side.
Never Kill A Boy On The First Date - S1-E5
Continuity mistake: The second time we see the van going towards Sunnydale, the creepy religious zealot guy puts his arm on the seat behind the mother and child. It then cuts to a closeup of them, and we cannot see the creep's arm behind them. It cuts back to a wideshot, and suddenly his arm is behind them again.
Never Kill A Boy On The First Date - S1-E5
Visible crew/equipment: When Buffy and Giles are in the cemetery, right before Buffy bails to go meet Owen, you can blatantly see a number rectangular studio/set lights reflected in Giles' glasses coming from various angles. (There wouldn't be dramatically-angled lights like that in a cemetery, let alone after dark).
Never Kill A Boy On The First Date - S1-E5
Continuity mistake: When Buffy gets up to walk over to Owen in the cafeteria, watch Willow and Xander... the directions they are facing change when it cuts to the wideshot. They suddenly are both watching Buffy in the wideshot, which they weren't before the shot cut. It's pretty subtle, so you have watch closely to notice.
Never Kill A Boy On The First Date - S1-E5
Continuity mistake: When Buffy, Xander and Willow are in the cafeteria in the beginning, Buffy says she's going to sit with Owen and Willow tells her "good luck." The way Willow is holding her fork changes between edits. (Specifically, it goes from pointed down to pointed up between cuts).
Chosen answer: He had larangitis and because of the shooting specifications they had to have him shoot the scene with a bad throat, they then re-recorded his lines and dubbed them. At various points during the scene and indeed the episode you can see him touch his throat or rub it.