Burt Lancaster was so immersed in his role that he wept on some moments, but he asked director John Frankenheimer not to show him cry to the audience.
Robert Stroud was actually imprisoned in cell #42 located in D Block. According to Frank Heaney, a former prison guard (1948-51), Stroud was anything but the sympathetic character portrayed by Burt Lancaster. He was an extremely difficult and demented inmate who, though highly intelligent, was a vicious killer and a violent psychopath.
The real Robert Stroud died a year after the film's release. He had been incarcerated for the last 54 years of his life (he died at the age of 73) with 42 of those years being spent in solitary confinement. He was never allowed to see the film about his life.
Due to this popular movie, the real Robert Stroud became one of the most famous inmates of the federal prison at Alcatraz, second only to mob boss Al Capone.
Burt Lancaster later claimed that Robert Stroud could not be released from prison because the authorities were concerned he might sexually abuse children.
Karl Malden: [name] Leavenworth warden Harvey Shoemaker introduces a new warden to the institution. He identifies one of the prisoners as "Sekulovich", Malden's own real name.