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)
Continuity mistake: New boss Lorraine unfolds her arms twice. (00:39:05)
Continuity mistake: Timothy is wearing disposable gloves as he is training Buffy at the grill, but in the shot when he puts the raw patties on the grill, he is barehanded. (00:16:15)
Continuity mistake: When Buffy's friends come visit her at work, WIllow is playing with some straws in a styrofoam cup next to the register which disappears a few shots later.
Continuity mistake: When Manny stamps Buffy's card in the time clock, he hands the time card to her with his right hand, but in the next shot facing Buffy, Manny hands the card to Buffy with his left hand.
Continuity mistake: When Timothy shows Buffy how to use the grill, there is a wood-handled grill press, and another tool, right in front of the button panel. However, after he says, "It eliminates variation," in the close-up as he presses the button, both tools as well as the transparent plastic glove he wears have all vanished. (Another mistake notes a different close-up with a disappearing glove.) (00:17:25)
Continuity mistake: When Buffy is assigned to the grill, as Timothy explains the process he's wearing a short-sleeved orange/white stripe uniform. In the close-up, when he places the second patty on the grill, Timothy is wearing a 3/4 sleeve, dark blue shirt. (00:17:15)
Continuity mistake: When Buffy is being offered the 'doublemeat medley' burger by her boss, the burger looks different in close up than in the long shots. In the close shot, the burger looks overall bigger, more filling is visible and there is more lettuce sticking out.
Continuity mistake: The finger changes position in Buffy's hand as she picks it up. (00:23:35)
Character mistake: At the end, the new manager tells Buffy that the burgers are ground up veggies with rendered beef fat. But earlier in the episode, when Buffy finds the severed finger, it shows chunks of beef being ground up.
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.
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 ★