The directors were only 16 years old when the production started and completed the film at 18 years old.
It was difficult to find eyewitnesses, as the few who remain were unwilling to speak. By chance, the filmmakers met an elderly woman on the street who, as a child, had seen the prisoners. She shares her memories in the film. Shortly after filming, she passed away.
The producers came across the tunnels in Peggau during their free time, not knowing what had happened inside--there was no indication of the site's past. It was only through work on the documentary that they slowly uncovered the history behind it.
In the film, a cemetery briefly appears as a symbolic representation of medieval graves. One of the tombstones bears the name "Werner Rois" - the mayor under whose leadership the memorial was established in 2006 and who has since passed away.
