According to Director John Sturges' inputs for the book of Emmanuel Laborie "Sturges: a filmmaker's story", John Sturges said he was frightened directing Spencer Tracy, who was a living legend. At the beginning, he was just stuck on the storyboard and choosing good camera angles, and did not dare to interfere in Tracy's way of acting. Until the day Tracy rehearsed a scene, while Sturges was looking at it through the eye-piece of the camera, suddenly took off his jacket and hung it on the camera lens blocking up Sturges' view. Then Tracy took Sturges aside and told "John, can you stop only worrying about your camera and take care about the actors, because the camera is only a hungry machine, and it will not be satisfied if you feed it with junk food".

Spencer Tracy personally got his good friend Pat O'Brien his role in this movie.

Although almost all of the film takes place in New York City, there is less than five minutes of footage filmed on-location in New York City.

Per Eddie Muller's TCM "Noir Alley" introduction in Jul 13, 2019, $5,000 was paid to Gustav Garfield avoid a plagiarism charge from a short story called "Murder in Jest" after the studio paid a reported $40,000 to NYC Asst. District Atty. Elezaor Lipsky for the script.

When the film began production, Pat O'Brien had largely been out of circulation in Hollywood.

When lawyer James Curtayne visits the Korvac family to ask them questions, they sit around the dinner table having supper. The Korvac family members speak among themselves in the Romanian language.