In the movie you see that every time these Sleepwalkers are before a mirror, the reflection reveals what they really are. When the two youngsters Charles and Tanya are having their picnic in the old graveyard, Tanya wants to take a picture of Charles using her reflex camera. Well, everybody knows that when you use a reflex camera you see the image to be shot through a mirror inside the camera. Why doesn't Tanya see the real face of Charles when she looks in the viewfinder?