Revealing mistake: Watch the shot of Glory as she is hit by the truck at the beginning of the episode (easier to see in slow-mo/frame-by-frame). She isn't hit by the truck at all. It goes right past her. A simple optical illusion used in filmmaking for decades.
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.
Continuity mistake: In the scenes where Buffy is being taught how to cook the burgers, the guy that is showing her has safety gloves on. In the close-up of the guy turning the burgers and pressing the buttons, the gloves are gone, and in the next shot, his gloves are back on.
Other mistake: After Gage turns into a monster and fights Buffy, the two monsters slide into an open grate. During the shot, there's some sort of weird "glitch" in the background where the garbage can and wall seem to slightly move. All I can assume is that a few frames were trimmed to speed up the shot and it may have exaggerated subtle camera movement, making the background appear to "jump" slightly.
Continuity mistake: When Buffy, Willow, and Cordy are talking at the swim meet (after Gage waves at Buffy), the way Buffy is holding her hands changes back and forth between two positions as it cuts between her and Cordy. Seems two different takes were used, and she had her hands in slightly different positions in them.
Continuity mistake: When Angelus is spitting out Gage's blood, he goes from straight up to leaned over between cuts.
Continuity mistake: After Willow says that the student was killed by being opened up like an Oreo "except without the chocolaty cookie goodness," Buffy's hands go from together to apart instantly between cuts. She then puts her hands back together only for them to be apart again in the next shot.
Continuity mistake: When Buffy is talking to Cameron in his car near the start, the amount of light on Cameron's face coming through the windshield changes between cuts a few times. Sometimes the top is up over his eyes, sometimes it's down by his nose, etc. Also, depending on the angle, sometimes there's a purple glow on his face and sometimes not.
Continuity mistake: When Buffy and the guy are talking at the beach in the beginning, right before they hear a voice scream "Somebody help me!", the guy starts to turn to look at the tide. However, in the next shot, he's instantly facing Buffy again and then turns to face the tide a second time.
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 ★