Revealing mistake: When Neil starts to sneeze, he carefully puts his hands close to his nose to give the impression that the green jet is coming from his nose. However, in one shot, just before the guys bag him we see the jet appearing from his hand while his hand is several centimetres from his nose.
Revealing mistake: When the vampire is shaving himself in the toilet, the reflection in the mirror of his shaving cream, clothes and gloves is almost, but not quite, identical to his movements. The empty suit in the mirror and the visible part in front of it were shot separately by copying the other part's movements as closely as possible, as the surviving raw footage can prove. It's hard to see, but there is a small difference between the motion of the hands.