Goofs

Near the beginning of the movie while the two detectives are driving down the road there is a white Dodge van behind them. In a moment it passes them. A moment later the same van is again behind them.

Blood on Warren's naked body keeps appearing and disappearing and appearing in different parts at climax of the film.

When Warren gets arrested by Leo Kessler, he is stark naked. When all the police cars arrive, Warren is wearing black underpants.

Just before Warren is shot in the head, his hair is messed up from running. When the bullet hits him, his hair is neatly parted with his forehead totally exposed.

When Warren is chasing Betty through the woods, he's wearing pants while running in some shots.

After Leo gets fired for planting evidence, the department would have undoubtedly confiscated his gun.

Warren's method of operation when killing was to be naked to avoid getting blood on his clothing. Despite this, he could have left other evidence (e.g. hair, footprints) at the scenes of each of his killings.

Instead of simply losing his job, Kessler would have been immediately arrested and charged for planting evidence, which is a felony under § 141 PC.

Warren was naked when he killed his victims to avoid getting blood on his clothing. Unless he showered to remove the blood prior to getting dressed, it would still be possible to have blood transferred to his clothing once he got dressed.

When Leo executes Warren in front of the other officers, he could have been taken into custody for murder because Warren was already subdued, and was merely announcing his intentions for an insanity plea. He was no longer creating an imminent threat for anyone at the scene.

When Leo comes into the dorm, and see's Doreen's body he screams his daughters name but instead of screaming Laurie it sounds like he scream's Holly instead.

When Bronson is walking to his kitchen at night, he crosses in front of a well-lit, out of frame window. Clearly visible in shadow form is the head of a crewmember wearing a baseball cap.

When Leo and Paul drive away from the Johnson's house you can see the crew members standing and sitting around.

After Warren accosts the two girls in the theater to create an alibi while he committed the murders, during the movie, officers are shown later interviewing the two girls at the station. There's no way the police could have gotten the two girls' names, since they apparently didn't know Warren.

At the end of the film, Warren is distracted by the transmissions on the police radio while searching for Laurie. The radio was given to Laurie by McAnn long before Warren is arrested for murder. Yet she still has it after his trial, when there is no reason for her to keep it following the arrest as it a tool to contact McAnn should Warren make another obscene call to her. Furthermore, no charging device is given with the radio, so the battery would have long been flat. It is highly likely that a property officer at the police station would also have noticed its absence for such an extended period and would have questioned McAnn as to its whereabouts for inventory purposes.

Kessler admits to McAnn that he planted the blood stains on Stacey's clothes. A cop of Kessler's years would never tell his partner (especially a new one) that he planted evidence.