All police officers depicted in this movie are from the fictional 53rd Precinct, the setting for Car 54, Where Are You? (1961) and Baretta (1975).
Jada Pinkett Smith turned down the role of Delilah. Her long-time friend, rapper Tupac Shakur, had been fired from Menace II Society (1993) after an altercation with Albert Hughes, one of the film's directors.
The film features five actors from Menace II Society (1993): Larenz Tate, Clifton Powell, James Pickens Jr., Ryan Williams, and Clifton Collins Jr.. Collins is credited as "Clifton Gonzalez Gonzalez."
It's not specifically stated, but Curtis, Cleon, and Skip belonged to a unit in the 1st Marine Recon Battalion. Late in the movie, Cleon wears a patch with the 1st Marine Recon Battalion insignia on it.
The cab driver at the beginning of the movie is a reference to Robert De Niro in Taxi Driver (1976).
Martin Sheen: as "The Judge". Sheen's appearance, and the fact that his character is a war veteran, is presumably a tribute to his role as a U.S. soldier in the Vietnam War in Apocalypse Now (1979). In this movie, he's a U.S. Marine where in Apocalypse Now, he was an Army ranger.