The pictures on social media show the actor, looking scruffy and in cuffs, in a new film called Escape from Pretoria. He is seen being escorted by uniformed guards.
The film is based on the memoir, Inside Out: Escape from Pretoria Prison, by Tim Jenkin, who was held at the prison - now part of the Kgosi Mampuru II Correctional Centre in the capital - during the 1970s.
At the time of his arrest, Jenkin was charged with “producing and distributing 18 different pamphlets on behalf of banned organisations” - including the ANC, SACP and Umkhonto we Sizwe - between 1975 and 1978.
He pleaded guilty and was sentenced to 12 years in prison. But in 1979, Jenkins, along with fellow inmates Alex Moumbaris and Stephen Lee, staged a daring escape.
The movie, directed by Francis Annan, who shares the writing credits with LH Adams, sees Radcliffe reunited with Harry Potter producer David Barron.
Portraying a South African political prisoner plays to his decision to steer clear of stereotypical characters.
Escape From Pretoria tells how Jenkin, Moumbaris and Lee cut wooden keys and used them to open a series of doors. They fled the country to Dar es Salaam.
Filming has been taking place in Adelaide, Australia, parts of which were adapted to resemble apartheid-era Cape Town.
According to reports, there were administrative hassles with filming in South Africa, hence the decision to film elsewhere.