This particular slip-up relates to the inconsistency in the tv-edited version of the movie. In the scene where "Drake" goes to the vampire store and is looking around, the young woman helping him has fishnet nylons on, then does not, then does again. In the scene, she is getting the "Dracola" out of the fridge, and has bare legs, then she walks back over to the other side of the room and has the fishnet nylons on once again.

I don't know if this is available on the special edition DVD, but on the tv-edited version this mistake is clearly visible.