Revealing mistake: During the fight scene at the end when Buffy is fighting the demons you see her throw one of the demons off the platform. If you watch him fall you can see him land safely on a conveniently placed mat. (00:38:10)
Revealing mistake: In the scene where Buffy is fighting the big scary lunch lady, look closely in the far away shots because you can see that the big lunch lady is now a skinny little stunt double. (00:41:55)
Revealing mistake: When Buffy runs in front of the car you can see knee pads on her knees. You have to look quite closely because they are the same colour as her tights. (00:15:00)
Revelations - S3-E7
Revealing mistake: In 'Revelations' when Buffy and Faith are fighting, the kick Faith aims at Buffy's face right after she says 'We can work this out' very noticeably misses, but Buffy still reacts as though it landed. (00:36:15)
Revelations - S3-E7
Revealing mistake: When Gwendolyn Post fights Angel in the mansion, she breaks a long-handled shovel over her knee to create a stake. If you watch in slow motion, the handle of the shovel is pre-broken (she simply holds the two pieces together tightly), and the pieces separate just before they actually make contact with her knee. (00:34:55)
Revealing mistake: When Buffy saves the man from being hit by a car, there is a very quick shot of the man standing in front of the car. In this shot, Buffy can seen on the left hand side of the screen running into the street to save him. But the shot then immediately cuts to Buffy who is suddenly still standing on the other side of the street with Lily and runs into the street to save him again.
Revealing mistake: During Faith's fight outside the Bronze in 'Faith, Hope And Trick' when she stakes the vampire, if you watch carefully, you can see the rubber stake bending. (00:15:20)
Revealing mistake: In the teaser of "Beauty And The Beasts", when Jeff is running through the woods, you can see in the top left corner of several shots a lamp being used to light the scene.
Revealing mistake: After Faith brings Angelus back, when she goes to punch him and he blocks, the stuntman switch is very obvious - he's noticeably taller, has different hair and doesn't even seem to be wearing any vampire make-up.
Revealing mistake: In Graduation Day Part One, when Faith shoots Angel with the longbow, you can see the false point spring out as if it were on a hinge from inside his jacket. (00:22:47)
Lover's Walk - S3-E8
Revealing mistake: Early on, Spike falls down drunk. He wakes up because his hand is on fire from the sunlight. When he runs away, a little bit of fire stays on the stones where his hand was when it started.
Revealing mistake: Near the end when the good Willow says goodbye to the evil Willow and hugs her, there is a shot of the back of the good Willow's head and the evil Willow's face. You can tell that the good Willow is a body double wearing a wig - there's something circular near her scalp, possibly an elastic band.
Revealing mistake: Towards the end, when Buffy stabs Faith, there is no blood whatsoever.
Revealing mistake: Near the end of the episode when the Mayor releases the vampire from his cage and lets him cut his head in half, you can tell that the Mayor's head is a still image when it fixes itself. The expression on his face doesn't change at all and looks completely unrealistic.
Revealing mistake: Right at the beginning of the episode, Buffy is sat outside with Willow and Willow is levitating a pencil. The pencil is obviously CGI as it stands out from the rest of the picture and doesn't cast a shadow. It also disappears from view whenever there is a side-angle shot of Willow.
Revealing mistake: Both the good and evil Willows' faces are barely seen onscreen at the same time due to them being played by the same actress, but when they occasionally are the good Willow stands out from the picture more than the evil Willow. She must have been filmed separately from the good Willow and edited in later.
Revealing mistake: When evil Willow licks good Willow's neck the neck that you see is a lot longer than either of theirs. Since both Willows' faces cannot be filmed at the same time a body double must have been used for this shot.
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 ★