Most of the outdoor city scenes for the movie were filmed in Saint Petersburg, Russia. This was for two reasons: one, the architecture of the city has many Germanic aspects, and two, there are plenty of streets with little or no modern advertisements and other commercial aspects.
Also helping Bruno Ganz in preparing for the role was the unique, only known recording of Adolf Hitler when he held a private conversation with Field Marshal Gustaf Mannerheim of Finland; at that time, he was a World War II ally of Germany against the Soviet Union. Hitler unexpectedly showed up to congratulate Mannerheim on his 75th birthday on June 4, 1942. Finnish intelligence agents secretly made the recording in a train wagon, as Hitler did not allow recordings nor photographs to be taken in private. Some eleven minutes of the recording feature relaxed, normal-tone talk in which Hitler generally describe his views about the war. One of two copies of the tape was discovered in 1992 and has since been studied by scientists and historians.
Bruno Ganz studied Parkinson's disease patients in a Swiss hospital to prepare for his role as Adolf Hitler.
Many of Adolf Hitler's lines are historically accurate, based on accounts from Albert Speer and Traudl Junge. Most of them, however, are from earlier dates.
In the opening scene of the film, where Traudl is being interviewed for the position of Hitler's secretary in late 1942, she introduces herself to him as Traudl Humps. However, in all scenes in the bunker in April 1945, she is referred to as Frau Junge. In June 1943, Traudl, with Hitler's approval, married Waffen-SS officer Hans Hermann Junge, who was subsequently killed in action in France in August 1944. Because the film jumps directly from 1942 to 1945, these events are not depicted. However, her name change is correct.