The man administering the polygraph test to convict Richard Conte was the inventor of the polygraph or lie detector machine, Leonarde Keeler. He played himself in the movie.

James P. McGuire served as a Technical Advisor on this film. He is the Chicago Times reporter who wrote the articles on which this film is based, and was the basis of the character played by James Stewart.

The "roundhouse" where Frank Wiecek (Richard Conte) is kept at the Stateville prison, was the only remaining panopticon still in use in the United States in the 1990s. It was closed in 2016, but the structure remains, due to its historical significance.

ON SCREEN: "This film was photographed in the State of Illinois, using wherever possible, the actual locales associated with the story." This was the first Hollywood-produced feature film to be shot entirely on-location in Chicago. Many famous landmarks, such as the Chicago Merchandise Mart, Holy Trinity Polish Mission, and the Wrigley Building (of chewing gum fame) on North Michigan Avenue, can be seen throughout the film.

The Chicago Daily Times merged with the Chicago Sun in 1948, the year this movie was released, and became known as the Chicago Sun-Times, which is still in business as of 2017.

ON SCREEN: "THIS IS A TRUE STORY". This film was actually BASED on a true story. Some elements, especially characters names, were fictionalized out of necessity, such as some central figures to the story were still living at the time of production, and had not given permission for their names to be used.

The beer McNeal is drinking when he comes home, is Nectar Premium Beer of Chicago, which is no longer in business.

Thelma Ritter's role as the police Captain's secretary was mostly deleted from the released print, but she can still briefly be seen and heard in one scene in which she tells P.J. McNeal (James Stewart) the Captain will see him in his office.

When McNeal tries to convince Zaleska to take the blame for the murder to exonerate Wiecek, Zaleska asks if he should name "Joe Doakes" as his partner. At the time, Joe Doakes was another name for "Joe Blow" or "John Doe."

"The Screen Guild Theater" broadcast a thirty-minute radio adaptation of the movie on October 7, 1948, with James Stewart and Richard Conte reprising their film roles.

Film debut of Kasia Orzazewski, who portrayed Tillie Wiecek, mother of Frank W. Wiecek.

Film debut of Joanne De Bergh, who played Helen Wiecek, wife of Frank W. Wiecek.

First credited film role of John McIntire, who portrayed Sam Faxon.

Alfred Newman, head of the 20th Century Fox Music Department from 1940 to 1960, is credited as the composer of the music accompanying this film, with Edward B. Powell, as Edward Powell, providing the orchestral arrangements. However, except for the Main Title and the underscoring accompanying the final narration leading into the End Title, there is no underscoring whatsoever, in keeping with the film's docudrama style.

Included among the American Film Institute's 2001 list of 400 movies nominated for the top 100 Most Heart-Pounding American Movies.

"Screen Director's Playhouse" broadcast a thirty-minute radio adaptation of the movie on December 9, 1949, with James Stewart reprising his film role.

E.G. Marshal, who has a small uncredited part in Call Northside 777 as Helen Wiecek's 2nd husband, and Lee J. Cobb, who plays the newspaper editor Brian Kelly, were costars in 12 Angry Men.

James Stewart and Thelma Ritter were also in Alfred Hitchcock's Rear Window.

The clock shown in the police station is a Seth Thomas, an actual brand of clock produced from the time of the company's founding in 1813 until 2009.

Moroni Olson and Paul Harvey appeared in Father of the Bride (1950) and Father's Little Dividend (1951).

In 1946 James McGuire and Karin Walsh, the real-life people on whom Jimmy Stewart and Lee J. Cobbs' characters were respectively based, won the prestigious Heywood Broun Award for excellence in investigative journalism for the Chicago Times for "stories helping free a man wrongly convicted of murder."

Approved, MPAA, certificate number 12397.

Frank's name, in real-life, was Joseph Majczek. After being released from prison in 1945, he worked as an insurance agent in Chicago. For his wrongful imprisonment, the State of Illinois awarded him twenty-four thousand dollars, which Majczek gave to his mother Tillie. Majczek eventually remarried his wife, with whom he had divorced while he was in prison. His last years were spent in a mental institution. He died in 1983.

The man imprisoned with Frank (Majczek), Tommy, whose name in real-life was Theodore Marcinkiewicz, was released from prison in 1950, five years after Majczek. Marcinkiewicz was awarded thirty-five thousand dollars from the State of Illinois for his seventeen years of imprisonment.