Plot hole: Spoiler: At the end of the film we learn that the girl is the wild animal, having been saved by the same doctor. Yet at the restaurant she is wearing a bare back dress and does not have the giant X-like scar on her back, like he has or the model has, who the doctor marries at the end.
Continuity mistake: When Marvin walks Rianna home after dinner, she stands in front of her door and crosses her arms asking him if he wants to come in. The camera angles from the front show her arms crossed, the ones from the back show her arms at her side. Happens throughout the scene.
Continuity mistake: Near the end of the movie, Marvin meets up with the doctor who tells him that something else is in the woods doing the killing. They both take off running and the doctor falls flat on his back. Marvin turns to go back to the doctor, and the doctor is now sitting straight up and not in the same spot he fell at.
Other mistake: When Marvin and Sgt. Sisk are driving in the squad car, Sgt. Sisk notices Rianna walking her dogs and attempts to pull the car over to the right alongside the curb, but is actually just sliding his hands across the steering wheel, not really turning the steering wheel.