Anachronisms: Supposedly set during 1955, modern day traffic signals can be seen in New Orleans.
Anachronisms: 1980s vehicles in 1950s Brooklyn.
Anachronisms: Harry direct dials a seven-digit phone number from a payphone. This wouldn't have been possible in the 1950s.
Anachronisms: The movie is set in January, 1955. When Angel goes to Sarah Dodd's Harvest clinic, he has a pistol in his briefcase, a Smith & Wesson model 38 Bodyguard, which was not manufactured until 1957.
Anachronisms: When Harry Angel makes his tape recording, he gives the date as 3 January 1955. Later he quotes from the television program, "The Mickey Mouse Club" (1955) which did not premiere until 3 October 1955.
Factual errors: The credit for "Extras Casting" is misspelled without the first T as "Exras Casting".
Revealing mistakes: When Angel discovers Margaret Krusemark's body, a pulse in her neck is clearly visible.
Continuity: When Harry Angel fills Epiphany's glass in the hotel, he puts less than half a glass of whatever is they're drinking. In the next shot, her glass is full.
Continuity: When Harry tries to avoid Ethan Krusemark's two goons by buying oysters he ends up on the floor being attacked by their dog. If you look carefully you will see that the oyster sellers hat appears and disappears off his head from one brief shot to another.
Continuity: During Angel's first meeting with Cyphere, Cyphere's cane switches from being in his hand to not being in his hand when the camera angles changes.
Revealing mistakes: When the two goons and the dog are attacking Harry and have him on his back, the bulge of a knee pad can be seen under his right pants leg.
Continuity: When Harry Angel impersonates an official (Harry Conroy) from the National Institute of Health at the private hospital just outside Poughkeepsie, at the end of his conversation with the nurse, his glasses disappear between the penultimate and final shots of the scene.
Continuity: In the scene in which Angel is tailing Krusemark onto the street car, we see the number "937" on the front of the car. When he exits the car we see "905" on its side.