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.
Character mistake: When Rianna introduces Marvin to the animals at the shelter, she says, "We have macaws," and then shows him Cosmo, saying, "My friend Cosmo is a parrot." This does not make sense because "parrot" is a broad group of several bird species, including both Cosmo and the macaws. Cosmo appears to be a type of Conure.
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.
Continuity mistake: When Rob is falling off the cliff in his car, the dents on the car appear, then appear somewhere else, then disappear completely, then appear again.
Visible crew/equipment: The scene where the Doctor decides to change Marvin's name to snowball and Marvin is wearing a cone around his neck, there is a guy walking around in the background while the Doctor is talking. Yet he only lives with animals.
Continuity mistake: Notice the hot girl Marvin's watching. She's facing forwards to pick up her keys then after a shot of Marvin suddenly she's facing him.
Continuity mistake: When Marvin pulls drugs out of the guy's pants they're in his right hand yet when he holds them up suddenly they're in his left.
Audio problem: The horse rider Marvin speaks to says "What?" yet his mouth never opens.
Continuity mistake: After Marvin's car lands for the first time, you see a tree beside the car, but as its rolling backwards towards the cliff, the tree disappears.
Other mistake: Marvin tells Rianna he will pick her up at 8 for their date, yet he is already at the bar waiting for her to arrive.