Continuity mistake: When Buffy comes in to talk to her mum about the CAT scan, we hear her shut the door behind her. We then cut to a shot of Buffy, and can see the door slightly ajar in the background. (00:10:30)
Continuity mistake: When Joyce is talking to Buffy about the shadow, after she says "sometimes weeks", she turns towards Buffy. In the next shot she's facing away from her, then turns to face her again. (00:10:55)
Revealing mistake: When Glory creates the demon snake thing, we see a CGI image of the creature, but Glory and Buffy are nowhere to be seen. When we are shown where they are standing, their position should have been visible when the snake demon was created. (00:27:05)
Visible crew/equipment: When Giles picks Buffy up in his car, you can see lighting and camera equipment on the right.
Answer: She has superpowers, ergo fast movement. The reason she outruns him so easily in "Touched" is that she stops trying to actually fight him and just dodges instead.
Shay