Continuity mistake: When Xander falls through the ground, he lands with his arm on, or very near a bit of wood, but in a closer shot of him just before he gets up, the wood's disappeared and other rubble has moved around too.
Continuity mistake: When Buffy and Willow are talking about the sham of Thanksgiving Day at the groundbreaking ceremony, on one angle (the one where Buffy's face is shown) there is a strong wind blowing, moving their hair about, but in the other (when you can see Willow's face) their hair aren't moving.
Revealing mistake: One of the arrows that Spike gets hit with passes through just below his left shoulder, but there are times when you can tell that it is a fake arrow because the part of the arrow sticking out at the front moves and the part at the back does not. Look at the arrow just after Buffy turns Hus into a bear.
Visible crew/equipment: During the scene of the siege at Giles', there is a shot where an Indian guy jumps through the window and helps himself by holding on to the sill. If you look to the left side of the screen, you can see it's a moving wall and that several hands of crew members are holding it so it doesn't shake.
Continuity mistake: In the scene where Anya is undressing a sick Xander in his basement, she lifts up his shirt and says 'Help me get your trousers off.' During the following conversation, in the close-up shots his shirt is lifted far up on his chest, but in the wider shots it's covering his whole stomach.
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 ★