Shirley Stoler was originally cast in the part of "Izzy's Wife", but was replaced by Judith Drake. Stoler's voice can still be heard at the end of the scene, singing the song, "I Cried For You".
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."
The old train Harry takes in to Louisiana we see pulling up in the scene change wasn't a working train and for filming it had to be pushed in by a proper train from behind.
Alan Parker claims that Robert De Niro's performance as Louis Cypher was so eerie and realistic that he generally avoided him during his scenes, letting him just direct himself.
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."
In the novel the entire story was set in New York. In the movie much of the action of the film occurs in New Orleans. This change was suggested to Alan Parker by William Hjortsberg himself.