Akira Kurosawa complimented director Sidney Lumet on the beauty of the camerawork and the whole movie. By this he meant that there is an elemental connection between the story and the techniques used. For example, background lighting is gradually phased out to make the characters stand out more towards the end of the film.
The film was budgeted at $10 million but Lumet completed it for under $9 million. At a Guardian Lecture at London's NFT shortly before the film's UK release, he revealed that the studio was furious with him for doing so since it created a major book-keeping problem for them.
The character of Daniel Ciello is based on real-life NYPD Narcotics Detective Robert Leuci. Leuci's testimony helped indict 52 corrupt detectives. After he quit the job, Leuci turned novelist and wrote the gritty police dramas "Snitch", "Odessa Beach" and "Captain Butterfly".
Along with The Godfather (1972), this is the only major Hollywood movie to be shot in all five New York City boroughs (Brooklyn, Queens, the Bronx, Staten Island and Manhattan).
Lumet wanted to direct the film because he felt it would be a more accurate portrayal of police than Serpico (1973).