This film and They Call Me Mister Tibbs! (1970) are notable as among the first sequels to a color cop movie, long before the first sequel to Dirty Harry (1971) came out. Even more remarkable, both of these films featured African-American protagonists.
The screenplay for the film is inspired by the legacies of real life Harlem gangsters Bumpy Johnson and Frank Lucas. The character of Joe (the fake Charleston Blue) resembles the actual Frank Lucas, who was a major drug dealer around Harlem and Newark, during the time the film was made. There are numerous parallels between the Charleston Blue persona and Frank Lucas, who was known for his "Blue Magic" brand of heroin.