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.
End Of Days - S7-E21
Visible crew/equipment: Right at the end, when Angel saves Buffy from Caleb, the shadow of a boom mic can be seen in the top left corner of the screen as Angel helps Buffy to her feet and says, "I was never much for preachers."
Plot hole: When Andrew wakes up, Anya mentions the First posing as Warren to make him kill Jonathan. Jonathan's body hasn't been found and the only time Andrew became ready to talk, he was knocked unconscious. They shouldn't have a clue about Jonathan's murder.
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?
Continuity mistake: When Buffy looks into the childrens' ward the sign on the door saying 'Basement Access' disappears and reappears between shots. (00:12:00 - 00:36:15)
Continuity mistake: The time on the clock, when Buffy spots Jonathan, changes dramatically between shots.
Continuity mistake: In the scene near the end when Faith is putting Joyce's lipstick on in the mirror and taunting her, it is obvious that the make-up department forgot to put Faith's tattoo on her upper arm. It's obvious if you watch back and forth between the mirror and the shot of Faith standing and turning, there is no evidence of a tattoo that has been established Faith has in the previous season.
Seeing Red - S6-E19
Continuity mistake: When Buffy is fighting Warren at the end, there are several shots when it's clear that it's a stuntman playing Warren. The stuntman is taller and slimmer than Adam Busch, and the shape of his face is different, as is his hair in the front.
Continuity mistake: Near the start of 'The Wish', the scene where Cordelia is talking to the Cordettes and meets Anya. During the close-ups of Harmony, Anya is standing to camera right of the brunette Cordette behind her. A few seconds later when the shot is further away Anya is standing camera left of the Cordette. (00:05:40)
Visible crew/equipment: The demons known as "The Gentlemen" always float about two inches off the ground. In one scene, two of them are moving through a park, and you can see the light blue cart they are standing on. (00:32:15)
Other mistake: As Spike follows Buffy into the hallway by her front door we see Spike's reflection in the mirror. Vampires do not have reflections, so Spike should not have been visible.
Continuity mistake: During the opening of the season 6 episode "Grave," Willow's nose starts bleeding and she gets blood on her upper lip. Over the next several shots the blood consistently keeps appearing and disappearing.
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)
Plot hole: In 'Graduation Day pt 2' the Mayor has his vampires stand at the bottom of the steps leading out of the school to stop any escaping students. The thing is, all the parents managed to escape out the side exits. Since the Mayor was expecting all the students to try and run too, why didn't he have these exits covered? (00:33:15)
Visible crew/equipment: When Dawn and the other girl are getting up after falling through the bathroom floor into the basement, you can see a man standing behind them towards the left side of the screen.
Deliberate mistake: After Jenny pushes the janitor's cart into Angelus and runs up the stairs, there's no physical way he could be waiting for her at the top of the stairs (even with vampiric speed). Joss Whedon has admitted in interviews that he put in this blatant continuity error as the situation is a staple of the horror genre (girl runs from villain, only to find him standing right in front of her).
As You Were - S6-E15
Continuity mistake: When Buffy receives her letter from UC Sunnydale it says her address is 1630 Crestview, this doesn't sync up continuity-wise with the episode The Body as she tells the 911 operator that her address is 1630 Revello. She didn't move so it's a definite mistake.
Revealing mistake: When Buffy is invisible and in the social office in "Gone", she is searching for the summer files, and you can see a thumb picking them up. (00:20:40)
Chosen answer: From what we see in the series, certain girls are identifiable as potential Slayers - Kendra clearly fell into this category. The identification method is presumably mystical in nature, but the Watchers' Council are pretty effective at that sort of thing, so they're quite good at tracking down the potentials ahead of time. Not perfect, though - it does appear that Buffy herself may have slipped through the net - certainly she had no inkling of what she was until she'd already taken on the role of Slayer. It is possible, however, that this was actually cultural - an American family would hardly be likely to turn over their daughter to some strange man for 'training', so the Watchers might have chosen to keep an eye on her covertly, whereas some other cultures (like Kendra's Jamaican parents) might be more willing to believe.
Tailkinker ★