The film's screen play was written by John Gregory Dunne and his wife Joan Didion. The picture was one of a number of script collaborations from the couple.
Real life historical 1940s Los Angeles locations used in the film included various LA churches, Echo Park, Union Station, Olvera Street, the Biltmore Hotel and Chinatown.
When the brothers discuss at the lunch counter Des's prior meeting of Lois Fazenda, the napkin which Thomas crumples in his hands suddenly appears on the counter on the reverse angle shot, then is back in his hands again as the scene ends.
When the detectives are taking the crime scene photographs, the photographer is using a "Super Speed Graphic". This model of the classic Speed Graphic was not produced until 1956. This part of the story takes place in ca. 1947.