Errors made by characters (possibly deliberate errors by the filmmakers): During a television news clip about the murders, the reporter says the Wonderland Murders is the most heinous since the Tate-Labianca murders in 1968. The murders took place in 1969.
Anachronisms: Within the first few minutes of the film, a second generation Honda Prelude is seen passing in the street. In 1981 when the film takes place, the Prelude was still in the first generation (1979 - 1982).
Anachronisms: At the beginning of the movie there is an overhead shot of Santa Monica Pier with a Ferris wheel. There was no Ferris wheel on the pier in 1981.
Continuity: When John picks up Dawn at Sally Hansen's they have sex in the bathroom. As they begin John pulls down Dawn's shorts and underwear. When Sally bursts in, they are still having sex, but Dawn's underwear is now back on.
Continuity: When John picks up Dawn at Sally Hansen's house, she has with her the little dog, but when they leave running down the stairs, she has nothing in her hands, while he has a briefcase. Then, when they are in the car, Dawn has the puppy back with her.
Revealing mistakes: While seated at the table talking to the police, the tattoo on David Lind's right wrist has definite edges on each side. It appears to be a band-aid type covering.
Anachronisms: Fox Plaza is visible in one of the montages. It wasn't built until 1987.
Anachronisms: When John returns to Dawn he sits down on the bed with a six-pack of Budweiser. The cans are of contemporary type and not the straight cylindrical type of the 1980s.
Anachronisms: The Chevrolet Caprice sedan that John Holmes was transported in to the hotel had the flush headlamps and the third brake light, making it a 1986 model.
Anachronisms: In the beginning of the movie a character is seen using a "brick" mobile phone. The first mobile phone (the Motorola DynaTAC 8000X) was brought on the market in 1983 and therefore such a phone couldn't be in use in 1981.
Continuity: When Billy Ward is interviewing Holmes, there is a scene leading into a flashback in which Holmes is shown with a freshly-lit cigarette. After the flashback, Holmes is shown with an unlit cigarette.
Miscellaneous: Towards the end of the movie, we are in Holmes' Chevelle driving towards the Wonderland apartment. The camera is inside the car and shows the rearview mirror was removed.
Continuity: When John leaves the hotel the night before the murders,he tells Dawn to lock up after him. She closes the safety lock. When John comes back early the next morning, he lets himself in.
Continuity: Dawn can be heard urinating into the soda can, but when she throws it out of the car, it sounds empty when it lands.
Anachronisms: Right after the opening credits of the movie when John pulls up to the wonderland house, on the right side, you can spot a spanking new Volvo S80 in a driveway of one of the houses next door.
Revealing mistakes: When Ron is enraged with John, while at Wonderland, he picks up some sort of entertainment component (VCR, Cassette Player, etc...) and throws it through the picture window which crashes into the street below. Not only were there no cables attached to the component but the picture window was actually showing shatter marks before it flew into pieces when being hit by the component.
Continuity: When John is being interviewed/questioned by Billy Ward, the cigarette's length actually keeps changing from long to shorter then back again.
Miscellaneous: Numerous characters are using torch style lighters throughout the film. Torch style lighters were not available in 1981.
Factual errors: In the beginning of the movie an over voice says that the Wonderland murders were the worst in L.A. since the 1968 Sharon Tate murder. The Tate murders actually happened in August of 1969.