The part of Sid Fletcher was played by John Bindon (1943-1993) who, when he wasn't acting, was a real-life London gangster, and frequent "guest" of Her Majesty's Prisons. John Bindon was well-known in the 1960s and 1970s as an actor who specialised in playing violent thugs. Off-screen, he was notorious for his violent temper and his habit of provoking fights in pubs for no other reason than to prove what a "hard man" he was. He was a gangster who was an associate of the Krays and the Richardsons. He ran a protection racket and worked as a drug dealer in the West London district of Fulham. He was also a friend of Princess Margaret whom he met on the Caribbean island of Mustique. Following the death of a fellow gangster, Johnny Darke, in November 1978 at a club in Fulham, he was charged with murder. He was acquitted of all charges at the Old Bailey but his notoriety put an end to his acting career and he drifted into obscurity. He died of AIDS in October 1993.

Michael Caine's character was called Jack Carter. According to the film's director, Mike Hodges, the stand-in used for Michael Caine during the filming actually was a guy named...Jack Carter

Early in the film, when Jack Carter is in the bar and asks for a "a pint of bitter...in a thin glass" there's a brief shot of an old guy raising his pint glass to the camera. Look carefully, and you'll see that the old guy has six fingers (five fingers and a thumb)

One of the most memorable things about Get Carter is its use of locations in and around Newcastle. (Indeed, director Mike Hodges even rewrote the script at some points to make use of the locations he'd found.) But what is not so widely known is that the book the film is based on - "Jack's Return Home" by Ted Lewis - was not set in Newcastle at all. It was set in Doncaster.

Michael Caine appears in the 2000 remake, which stars Sylvester Stallone as Jack Carter.