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: When T.J. types in his height instead of Floyd's while searching for his dad's date on the computer, he never pressed the "Enter" key.
Other mistake: At the start when the Lexus is found it is shown as a mirror image as can be seen by the badge and registration number. (00:03:57)
Opera House Murder Case: File 2 - S1-E22
Other mistake: When Okata discovers the clue about the first murder in the recording room, the shadow cast in close-up is different from the wider angle - and it's also an impossible one, because the only light in the room is the one of her own flashlight, which couldn't be angled at the trolley that way. (00:11:25)