The film's release was delayed by more than a year because Warner Bros. wanted to clear a backlog of war-related films before releasing this timeless story, even though a cut had already been shown to servicemen overseas in 1945.

There was no finalized screenplay during filming, with Leigh Brackett and William Faulkner writing alternating sections of the initial draft before Jules Furthman and director Howard Hawks rewrote material during production, partly to appease the Hays Office censors.

Midway through filming, Hawks and the cast realized they couldn't tell whether chauffeur Owen Taylor had been murdered or committed suicide, so they sent a telegram to author Raymond Chandler asking him directly — and he admitted he didn't know either.

Filming was continually delayed past its planned late-November finish because of Humphrey Bogart's heavy drinking during his tumultuous divorce from wife Mayo Methot, which stemmed from his affair with co-star Lauren Bacall.

Nina Foch tested for the role of Carmen, but Hawks instead cast Martha Vickers after seeing a modeling photo of her, and later convinced Warner Bros. to buy out her contract with Universal.

Sonia Darrin's screen credit as Agnes was removed after the film's completion because studio head Jack L. Warner got into a feud with her agent, Arthur Pine.

Pat Clark originally played Mona Mars, but was unavailable when scenes were reshot in January 1946, so Peggy Knudsen replaced her; the 1946 opening credits still list Knudsen even though Pat Clark's original footage exists in the 1945 cut.

After Bacall's 1945 film Confidential Agent flopped with critics panning her acting, her agent Charles K. Feldman pushed Warner Bros. to reshoot scenes with Bogart in early 1946 to boost chemistry and capitalize on the 'Bogie and Bacall' phenomenon, with uncredited writer Julius Epstein penning the new scenes.

Wartime rationing subtly appears in the film: dead bodies are referred to as 'red points' (a nod to meat rationing) and Marlowe's car displays a 'B' gasoline rationing sticker indicating he was allotted extra fuel as essential war-related personnel.

Due to Hays Code restrictions on depicting homosexuality and pornography, the novel's plot point of Geiger selling pornography and having a relationship with Lundgren was removed, and Carmen's nudity was replaced with cryptic references to photos of her in a 'Chinese dress' and 'Chinese chair'.

The original 1945 cut was rediscovered in the mid-1990s at the UCLA Film and Television Archive, having originally been distributed to troops in the South Pacific; benefactors including Hugh Hefner and Turner Classic Movies funded its restoration and 1997 theatrical re-release.

Raymond Chandler praised Martha Vickers' performance in the 1945 cut, feeling she overshadowed Bacall, and believed the trimming of her scenes for the 1946 release was done deliberately to enhance Bacall's part.