When Louis blows salt from his egg onto the restaurant table, Harry Angel takes a pinch and throws it over his left shoulder. The superstition is that by doing so you blind the devil (or your evil angel).
When producer Alan Marshall first approached 'Robert de Niro' by phone about taking a part in the film, de Niro asked him "Are you the guy who produced Birdy (1984)?" When Marshall replied that he was, de Niro promptly hung up.
When Harry Angel visits Margaret Krusemark for the first time, Margaret orders her maid to bring them tea; she and the maid speak briefly in French, which Angel obviously doesn't understand. The maid is asking "Should I bring out the best cups?" and Margaret responds "No."
Fangoria article about the movie from the time when it was released had a pictures of deleted death scene of Herman Winesap. On one picture director Alan Parker is shown sitting next to the headless corpse with blood all over the room. Same article also shows picture of partially burned body of the journalist woman who slept with Harry earlier in the movie laying next to the burned house.
In the film, private detective Harry Angel (Mickey Rourke) searches for someone called Johnny Favorite. About two years after this film debuted, O'Rourke starred as the title character in Johnny Handsome (1989).
A reference to the movie was included in Polish metal band Hunter's song "Armia Boga" (Pol, "God's Army") from the album HellWood. The song ends with a phrase in English: "Welcome to my greedy Louis Cyphre's private hell."