Most of the street scenes were shot on location in New York without the public's knowledge. Photographer William H. Daniels and his uncredited assistant Roy Tripp filmed people on the streets using a hidden camera from the back of an old moving van. Occasionally, a fake newsstand with a hidden camera inside was also set up on the sidewalk to secretly film the actors. Director Jules Dassin hired a juggler to distract the crowds, and also hired a man to occasionally climb up on a light post and give a patriotic speech, while waving an American flag to get the crowd's attention.
Producer Mark Hellinger, who narrates the movie, died of a heart attack before the film was released. Following his death, Universal Pictures executives were ready to scrap the movie. They had no idea how to market it, and feared it would be a box-office failure. However, Hellinger's family reminded the studio that his contract for the film included a "guarantee of release" clause from Universal. Having no choice, Universal released the film in theaters, and was surprised when it became a hit and received two Oscars.
The basic plot of the film was the basis of a case players can solve in the video game, L.A. Noire (2011), released on May 17, 2011 by Rockstar Games. In the game the story is moved to 1940s Los Angeles.
Both Paul Ford and John Randolph were working on the New York stage in the hit drama "Command Decision" (which itself would be produced by MGM as a Clark Gable vehicle) when they appeared in this film, which was shot on location in the city.
In the scene where Muldoon and Halloran are shown entering an apartment house on Park Avenue, the awning shows the address "478". The building is actually 480 Park Avenue, one of the residential buildings designed by noted architect Emory Roth.