Other mistake: Just after Giles becomes completely blind, Spike gets up to get a book off of the mantle. When he does this you can, very briefly, see James Marsters reflected in the glass doors of the bookcase that was behind him, despite Spike being a vampire. (00:27:00)
Other mistake: In the scene where Spike escapes from a blind Giles, he pushes Giles out of the way and does not get a shock to the head from the chip in his head, which normally goes off with the most minor hint of violence.
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