Continuity mistake: When Genie is being seduced by the demon in Tim's car, her bra strap keeps going up and down. One moment it's on her shoulder, then it's not, then it's back on her shoulder again.
Continuity mistake: Genie removes her bra, however her bra straps reappear and then disappear while she is listening to the "Peace Offering" tape.
Continuity mistake: In the scene just before Sammi appears, the can of Pepsi falls over the record that is playing backwards. Then after Sammi disappears Eddie smashes the stereo there is not a drop of liquid anywhere.