The prison sequences were filmed in the abandoned Kilmainham Jail in Dublin, which was also used for " The Italian Job" and " McVicar".
"Sitting Target" was one of the first British films to be given an "X" certificate (which prohibited under 18s) for its violence alone. In spite of that, the B.B.F.C required a few cuts to be made before allowing the film to be released.
The Mauser Schnellfeuer with telescopic sight used by Oliver Reed was created by Bapty & Co., a British company that provided prop guns to the film industry in the U.K. The same Mauser prop gun was used in "Brannigan (1975) and The Disappearance (1977).
Jill Townsend and the actress who plays Jill St. John's neighbor both would appear on the first episode of The Sweeney.
The year this film was released, Edward Woodward's series of "Callan" was drawing to a close.