Leo Gordon had served five years for armed robbery at San Quentin State Prison. For this reason, Heinze, the Folsom warden, originally objected to Gordon appearing in the film, but director Don Siegel was able to convince him that Gordon was no threat to the prison.
Producer Walter Wanger served a four-month prison term for shooting agent Jennings Lang, whom he suspected of having an affair with his wife Joan Bennett. The experiences he had in prison so unnerved him that upon his release he resolved to make a film about what prison was "really" like,
At the time this was produced (1953-54), the Production Code was in full force. The Code prohibited any direct references to homosexuality. That's why the dialog subtly refers to keeping young inmates away from "certain prisoners."
This was such a financial and critical success for "Allied Artists" (formerly "Monogram"), they were able to book the film into theatres well into the late 1950s.
Actual inmates who were incarcerated and guards at Folsom State Prison at the time this movie was made are featured as extras.