This movie was filmed around Pittsburgh, Pennsylvania, beginning on January 13, 1992. Marie is checking into a motel with Joe Gennaro. Marie asks him, "We have a deal? We'll be staying till sundown -- 7:17 p.m." Since this is winter-time, sunset would be more like 5:30 p.m.
When Manny (in hospital) dies and becomes a vampire, his heart briefly stops, causing the EKG to sound an alarm before it starts beating again. He then wakes up and detaches the EKG leads, which ought to trigger another alarm but does not.
Vampires are not suppose to reflect in mirrors.