An important shot of Chopper walking down the street towards the camera, in slow-motion, and with everyone else in the shot out of focus is filmed in exactly the same manner as a similarly important shot of Travis Bickle in Taxi Driver (1976).
Well-known Australian singer/songwriter Billy Thorpe was strongly opposed to the use of his version of "Somewhere Over The Rainbow" in the opening credits. The makers chose to use "Don't Fence Me In" instead. Interest in the writers of the latter song was increased substantially by the song's use over shots of a prison.
Eric Bana admitted to eating junk food for four weeks to put on the extra weight needed to play the 1986 Chopper.
As everyone probably knows, "Somewhere over the Rainbow", the original song to accompany the opening credits of "Chopper", was written especially for the 1939 film version of The Wizard of Oz (1939). Curiously, in L. Frank Baum's original stage version in 1903, the Tin Man was referred to as (Mick) Chopper.