Continuity mistake: After Buffy finds Morgan's brain, Willow pulls up Morgan's school file on one of the library computers without even touching the keyboard. One moment the monitor is on the desktop, the next it's showing Morgan's file.
Continuity mistake: In the episode 'Teacher's Pet', when Ms. French is eating her bug sandwich, her sleeves go from being up in the long shots to being pulled down in the close-up of the sandwich. (00:24:05)
Welcome To The Hellmouth (1) - S1-E1
Continuity mistake: When Giles is giving his speech about the Hellmouth the books Buffy's holding keep changing from facing him to facing Buffy and back again. (00:18:20)
Continuity mistake: Buffy's birthdate starts at 1979. In "I Robot, You Jane", when the demon pulls up Buffy's file in the school system, it shows her year of birth as 1980 and her year as sophomore. But when her file comes up on the student's computer screen, it's changed to 1979 and that she is a senior. It wasn't until towards the end of season 1 in "Nightmares" that her birth year is 1981 (on her tombstone before she comes out as a vampire). (00:08:30)
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)
Continuity mistake: When we see Miss French make herself a bug sandwich, there are two, maybe three bugs left on her plate as she folds the bread. But when she eats the sandwich her plate is empty.
Nightmares - S1-E10
Continuity mistake: In the season 1 episode "Nightmares", Buffy is talking to Willow about her mom's divorce and she shuts her locker. A few seconds later she shuts her locker again. (00:02:55)
Continuity mistake: When Buffy finds Dr. Gregory's glasses on the lab floor she places them on the table, from the long shot she places them at the left end of the table near a plastic tub with a white lid, with the glasses open. Then it cuts to a close up where they are in front of a book on the right side of the table and are closed. Then cut back to the long shot and they are in the original place. (00:10:25)
Nightmares - S1-E10
Revealing mistake: The Master's artificial thumbnail is visibly falling off in a few shots of the opening teaser. (00:01:30)
Out Of Mind, Out Of Sight - S1-E11
Visible crew/equipment: At the very end, as the invisible girl gets taken along a corridor by the FBI agents, check the top of the screen - a boom mike creeps in as the agent says his line, then is withdrawn.
Continuity mistake: When Buffy drowns in Prophecy Girl, she falls into the pool with her hair tied in a ponytail and her arms under her. When she is discovered by Angel and Xander, her arms are by her sides and her hair is loose. (00:33:55)
Visible crew/equipment: When Catherine and Amy get switched back to their original selves, Catherine takes the fire axe that Amy is holding by using her powers. The wire used to pull the fire axe towards her as Amy holds it up and says "Mom! Please!" is visible.
Plot hole: In "I Robot, You Jane", how exactly does Willow scan Moloch out of his book when the scan is only about two thirds the width of it? (00:04:25)
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.