After Buffy kills the two vampires at the cemetery, Pike is seen in his apartment. Benny, who is now a vampire, knocks on the window and starts a conversation. Although this the movie subscribes to the notion of vampires not casting reflections, Benny has one as he floats outside Pike's window.
This is supposedly true about vampires, but the film never actually mentions this point. And also, it may be a little difficult for the film makers to completely get rid of Benny's reflection (played by the scrummy David Arquette) due to impossibilities such as he isn't a real vampire and only an actor.
Actually, the movie does support this aspect of vampire mythology. Later, Pike is in his van and two vampires approach from behind. He sees them when he looks over his shoulder, but not in the rear-view.