The name of the main character in the movie, played by Mickey Rourke, is "Stanley White" (it is said he is of Polish descent and changed it from "Wizynski"). In the closing credits, there is a Stanley White credited as "Technical Police Consultant".
Director Michael Cimino and co-screenwriter Oliver Stone envisioned either Nick Nolte or Jeff Bridges in the lead role. After seeing Rourke in The Pope of Greenwich Village (1984) and working with him on Heaven's Gate (1980), Cimino decided on him.
The exterior shots of New York City were actually sets built in North Carolina. Said sets proved realistic enough to fool even Stanley Kubrick, who attended the movie's premiere. Co-writer/director Michael Cimino actually had to convince the Bronx-born Kubrick this film's exteriors were shot at a sound-stage and not on location.
When Connie is in the bathroom before she is killed by intruders, there are 2 red spots on the lens, one on the right and one on the left. These are probably from a previous shot where fake blood got splattered on the camera lens and the operator failed to notice it.
After Connie is killed in the bathroom and Kearney and Lou enter Stanley's house to serve him papers, we see the outline of Connie's body with fresh blood on the bathroom floor. Blood turns a darker/brownish color after it is exposed to air, especially the time it took after Connie's murder and the beginning of this scene.