Began and finished filming in 1991. Although it was released almost a month after Murray's lead role in Groundhog Day (1993), he had actually finished filming this movie before the former began filming. Universal was going to release the film in early 1992, but it ended up setting on the shelf an extra year.
This the third time that David Caruso has portrayed a cop on film. His debut was in First Blood, where he played a deputy and prior to this film, he was a cop in King Of New York which was released a year before this film began production in the Summer 1991.
David Caruso who plays Robert De Niro's Detective friend and partner in the film, would go on to play another cop in the hit TV series, NYPD Blue, which would premiere seven months after this film was finally released. Filming on the show actually began around the time this film was in theaters, March 1993.
David Caruso and Tom Towles, who plays Kathy Baker's abusive boyfriend the film in which Caruso actually does his own brand of police justice in the film, would be featured on NYPD Blue, months after this film was released. Caruso would go on to play Detective John Kelly for a season and a half before leaving the show and Towles would be featured during the show as Lt. Anthony Lastarza, an ambitious and corrupt commander of the organized crime unit in which Caruso butts heads numerous times.
The film began production in Chicago during the Summer of 1991, which ironically was around the same time frame as Robert DeNiro's latest film, Backdraft was released in theaters by the same studio that produced this film, Universal Pictures.
The trivia item below may give away important plot points.
According to producer Steven A. Jones, the original ending has Milo beating Mad Dog in their fight. But test audiences could not accept seeing Robert De Niro getting beaten up by Bill Murray. Universal insisted that the fight scene be reshot and the film was delayed for a year. De Niro and Murray had taken the roles specifically because they were different than the type of roles audiences expected of them. The test audiences also felt that Glory was an unsympathetic character, so further reshoots were done to portray her as a victim of Milo's control.