Actor-Shared Background: Alex Rocco was a native of Somerville who'd been associated with the real Winter Hill gang the book and film are based on. He'd even been detained and questioned over the murder of Charlestown Mob member Bernie McLaughlin, an incident that had touched off the Boston Irish Gang War of the 1960s.
Looping Lines: The film has a few moments of obvious looping, including when Coyle states his age and when Brown first meets Andrea.
Those Two Actors: Robert Mitchum (Coyle) and Richard Jordan (Foley) play similar roles and share a similar dynamic in The Yakuza, a similar movie filmed almost immediately following The Friends of Eddie Coyle. The two films' scores were even composed by the same man: Dave Grusin.
