The actual Art Deco apartment building used in the film (located at 1360 Montgomery St in San Francisco) is still standing as of December, 2008. The actual apartment is marked by a cardboard cut-out of Humphrey Bogart, which can be seen from the street. The site is visited frequently by fans of vintage film noir.
Humphrey Bogart's complete uncovered face is not seen clearly until 62 minutes into the movie, when his character finally removes his bandages and looks into a mirror. All previous scenes with the character are either shown from his point of view or have his face obscured with shadows or bandages.
The playing on the phonograph of "I Guess I'll Have to Change My Plan" as Vincent is recuperating at Irene's apartment after his surgery may have been an arcane wink to the audience. It was used in "The Big Sleep." In that movie it was played when Vivian Rutledge (Bacall) pays off Marlowe (Bogart) at the gambling joint-nightclub.
Warner Brothers studio head Jack Warner was not pleased to discover that the face of one of his biggest stars, Bogart, is not seen for the first half of the movie. But the time Warner knew this, the film was too far along to be changed.
Between the film's unorthodox "first person perspective" and Bogart's negative press from his support of the Committee for the First Amendment established in the face of the hearings being done by the House Un-American Activities Committee led to the film having a poor performance at the box office.