Once More, With Feeling - S6-E7
Continuity mistake: When Buffy jumps off the stage in the Bronze that Dawn and Sweet are on and starts dancing, one of Sweet's goons that is lying unconscious moves from the far left of the bottom of the stage to the far right between shots.
Continuity mistake: After Buffy decides not to take the antidote to the demon's venom, we cut to a scene at the mental institution. She says she wants to go home with her mum and dad. As she says this her dad puts his hand on Joyce's left arm. In the following shot, Joyce suddenly has her right hand on top of his when it wasn't in the previous shot.
Once More, With Feeling - S6-E7
Continuity mistake: From the start of the second scene in the Magic Box, the doughnut and cruller on Xander's plate constantly switch places. (00:03:35 - 00:05:50)
Seeing Red - S6-E19
Continuity mistake: Shortly after Spike tries to rape Buffy, he returns to his crypt and drinks a glass of vodka. Clem then arrives to watch television with him. During Spike and Clem's conversation, the position of the bottle of vodka constantly changes between shots.
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: 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.
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.
Seeing Red - S6-E19
Continuity mistake: When Tara got shot, the blood on Willows shirt was spread out, but in the next shot, there were big clumps of blood.
All The Way - S6-E6
Continuity mistake: When a vampire kicks through a car window trying to hit Buffy, some shards are still standing in the window frame. The angle changes, and the shards are gone. (00:37:00)
Tabula Rasa - S6-E8
Continuity mistake: When Buffy and Dawn are discussing Buffy's new name choice Dawn's hair changes repeatedly between shots. First it's over her shoulders, then behind, she has a clip in one shot, then she doesn't.
Continuity mistake: As Buffy is being trained at the register, the receipt at the top of the register switches in every shot. (00:07:45)
Life Serial - S6-E5
Continuity mistake: When Buffy and Spike are in his crypt drinking whiskey, after Buffy says to him, "You have had so too much to drink at this point, I am cuttin' you off", she drinks a shot twice between shots.
Continuity mistake: When the Buffybot is at the parent teacher day and she is looking at the student model of a Utopian city, the hover cars are moving around the model on a wire. But when the shot changes, the cars aren't moving. Then in the next shot, they're moving again.
Tabula Rasa - S6-E8
Continuity mistake: In 'Tabula Rasa' when the loan shark's henchmen throw a stake at Spike at the start it flies over his head and hits a tree. But, if you compare the angle they approach from with the relative positions of Spike and the tree you can see it would have had to do a 90 degree turn in mid air to fly over his head before hitting the tree. (00:01:00)
Continuity mistake: When Dawn was at the house, she had a grey top and a red skirt, but outside, she had a red top and black pants.
Life Serial - S6-E5
Continuity mistake: While working at the Magic Box, Buffy's horseshoe necklace constantly shifts between left, middle, and right positions, even within the time loops. (00:20:20)
Continuity mistake: In Bargaining, part 1, Anya is talking to Giles while he trains the Buffybot. There's a shot from behind and we can the corner of her jumper move around as she turns away, then it cuts back to a front view of her and she's still facing Giles. (00:26:20)
Continuity mistake: The episode begins the morning after Buffy and Spike first have sex. That night, Willow and Amy go out again to find Rack's place, and this cuts directly to Willow waking up the next morning. But later in the episode, Spike makes repeated references to what happened between him and Buffy "last night", when in fact it was two nights ago.
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 ★