The Police Battalion Bozen is shown in the film as a Waffen-SS formation, complete with full SS uniforms and insignia. In reality, this unit was a German Police unit and its members wore regular police uniforms and were not considered part of the Waffen-SS.
Major Hellmuth Dobbrick was not present at the Via Rasella attack on the 11th SS-Police Company, as is shown in the film. The 11th company was commanded by First Lieutenant Wolgasth (who is not mentioned in the film), while Dobbrick commanded the entire 3rd battalion comprised of five police companies.
All of the SS officers in Kappler's Security Police headquarters are shown to be wearing the Knight's Cross of the Iron Cross, which was a high level decoration for valor and heroism in combat. It would have been highly unusual for so many security officers to have this award, since the Security Police dealt with "behind the lines" actions and not front line combat.
The film portrays General Kurt Mälzer as an impulsive and hardcore Nazi, whilst Herbert Kappler is depicted as a tired worn out man who believes that the fall of Nazi Germany is imminent. In reality, Kappler was a zealous Nazi responsible for hundreds of round-ups, executions, and reprisals, whilst it was Mälzer who was a reserved officer, cautious about implementing harsh policies.
When the German soldiers are first shown marching around the city (not at the time of the bombing), just after the old woman is seen looking out of the window at them, one of the soldiers in the row furthest from the camera is marching out of step with all the others.