The stunt double's face is seen close up during a fight scene between Buffy and some vampires.
When Buffy and Faith kick in the blinded window, you see a vampire on the floor with his legs in the sunlight. However, his arm, which is in the shade, catches fire.
When Faith is thrown against a tombstone, it shakes a little bit revealing it to be a prop.
In the intro fight scene, after the last vamp has chopped off Buffy's stake with his bigger sword, when they go in close, Buffy is unable to block the left arm with his short sword but he withholds the stab himself (revealing they are actors unwilling to kill each other.)
Buffy tells Giles and Wesley that she doesn't think the vampires she and Faith fought were part of the same group, even though they all wore the same uniforms.
In the crypt, when Buffy is surprised by several vampires, she jumps into a stone sarcophagus to hide, closing the lid while they are already entering. In the Buffy universe, vampires are supposed to have an unnaturally heightened sense of hearing so they should have heard that and discovered her.