This movie was inspired by the memoir of Slavomir Rawicz depicting his escape from a Siberian gulag and subsequent four thousand-mile walk to freedom in India. Incredibly popular, it sold over five hundred thousand copies, and is credited with inspiring many explorers. However, in 2006, the BBC unearthed records (including some written by Rawicz) that showed he had been released by the U.S.S.R. in 1942. In 2009, another former Polish soldier, Witold Glinski, claimed that the book was really an account of his own escape. However, this claim too has been seriously challenged.
When Janusz Weiszczek and the others spot the tattoo of Vladimir Lenin and Joseph Stalin on Valka's chest, he angrily replies that they were great men. Such tattoos were in fact employed by criminals in the false hope that they wouldn't be shot there as it was supposed to be illegal to deface an image of either Lenin or Stalin. Although it is well-known that the executions were conducted via shooting in the back of the head.
The 53,820-square-foot Gulag Camp was built at Nu Boyana Studio in Sofia, Bulgaria, and is still (as of 2015) maintained by the studio and available for filming.
In the end credits it says, that this movie was only "inspired" by Slavomir Rawicz's book "The Long Walk" (1955), not "based" on it. This movie never claims to be a "true story", but rather to be informed by historical research. Peter Weir only took the basic storyline of Rawicz's popular book, but changed the names and added other characters and events based on historical sources. The central character doesn't represent the real-life Rawicz, therefore his name was changed to "Janusz Wieszczeck". The character "Valka" is not in Rawicz's book at all.