In order to get distribution for his film, Martin Scorsese was told to add nude scenes so it could be promoted as a "sexploitation" movie. He thus shot the fantasy scene showing J.R. imagining encounters with prostitutes.
There is no question mark in the title. Having a question mark in the title of a movie is considered bad luck in the industry.
Martin Scorsese's mother, Catherine Scorsese, appears briefly as J.R.'s (Harvey Keitel's) mother cooking at the beginning of the film, and serving food near the end. Mrs. Scorsese continued to appear in many of her son's films, until her death in 1997. Scorsese himself appears uncredited as one of the gangsters. To this day, he still makes cameo appearances in many of his films.
Harvey Keitel's first credited screen role. He would go on to work with director Martin Scorsese five more times.
Harvey Keitel often played the lead role in the debut features of future acclaimed directors. Apart from Martin Scorsese's debut, he also was the lead in the first features of Ridley Scott (Les Duellistes (1977)), and Quentin Tarantino (Reservoir Dogs (1992)), for example.