The Big Sleep is known for its convoluted plot. During filming, allegedly neither the director nor the screenwriters knew whether chauffeur Owen Taylor was murdered or had killed himself. They sent a cable to Chandler, who told a friend in a later letter: "They sent me a wire ... asking me, and dammit I didn't know either".
After its completion, Warner Bros. did not release The Big Sleep until they had turned out a backlog of war-related films. Because the war was ending, the studio feared the public might lose interest in the films, while The Big Sleep's subject was not time-sensitive. Attentive observers will note indications of the film's wartime production, such as period dialogue, pictures of President Franklin D. Roosevelt, and a woman taxi driver, who says to Bogart, "I'm your girl." Wartime rationing influences the film: dead bodies are called "red points", which referred to wartime meat rationing, and Marlowe's car has a "B" gasoline rationing sticker in the lower passenger-side window, indicating he was essential to the war effort and therefore allowed eight gallons of gasoline per week.
The "Bogie and Bacall" phenomenon, a fascination with the couple that had begun with To Have and Have Not, and that grew during their subsequent marriage, was in full swing by the end of the war. Bacall's agent, Charles K. Feldman, asked that portions of the film be re-shot to capitalize on their chemistry and counteract the negative press Bacall had received for her 1945 performance in Confidential Agent. Producer Jack L. Warner agreed, and new scenes, such as the sexually suggestive racehorse dialogue, were added (scripted by an uncredited Julius Epstein). The re-shot ending featured Peggy Knudsen as Mona Mars because Pat Clark, the originally cast actress, was unavailable. Furthermore, the parts of James Flavin and Thomas E. Jackson were completely eliminated. Because of the two versions created by the re-shooting, there is a substantial difference in content of some twenty minutes between them, although the difference in running time is two minutes. The re-shot, revised The Big Sleep was released on 23 August 1946.
The cinematic release of The Big Sleep is regarded as more successful than the 1945 pre-release version (see below), even though it is confusing and difficult to follow. This may be due in part to the omission of a long conversation between Marlowe and the Los Angeles District Attorney where the facts of the case, thus far, are laid out. Yet movie-star aficionados prefer the film noir version because they consider the Bogart-Bacall appearances more important than a well-told story. For an example of this point of view, see Roger Ebert's The Great Movies essay on the film.
Novelist Raymond Chandler said Martha Vickers (Carmen) overshadowed Lauren Bacall (Vivian) in their scenes together, which led the producers to delete much of Vickers' performance to enhance Bacall's.