Peter Boyle found it very difficult to draw a glass of tap beer for his part of a bartender. Director Peter Yates arranged for a correctly-filled glass to be available for Boyle below the camera line. Unseen by the camera eye, Boyle then switched glasses,
This film is based on the George V. Higgins novel of the same name. Higgins also wrote Cogan's Trade, on which the film Cogan: Killing Them Softly (2012) is based. The character 'Dillon' appears in both, played by Peter Boyle in this movie and by Sam Shepard in Killing Them Softly.
One of the reasons Steven Keats was cast by Peter Yates is because Yates thought Keats looked like Mick Jagger.
Alex Rocco, who plays bank robber Scalise, was a former member of the notorious Winter Hill Gang that operated out of Boston, Massachusetts. Moreover, Rocco introduced Robert Mitchum to Howie Winter, who was the second boss of the Winter Hill Gang, to help Mitchum research his role as Eddie Coyle.