In the opening scene there is a shot of a man wearing a hat walking with a woman across a bridge. The man is stopped by a soldier and motioned to go back the way he came. The man is the real Jack Zimmermann, the youngest of the 13 being hidden.
The Podgórska sisters, Stefania Podgorska (1925 - 2018) (Stefania Podgorska Burzminski) and Helena Podgorska (born 1935), came from a Catholic farming family living near Przemysl in south-eastern Poland. During the Holocaust, 16-year-old Stefania and her seven-year-old sister harbored 13 Jewish men, women and children in the attic of their home for two-and-a-half years. Both were later honored as the Righteous Among the Nations by Yad Vashem as well as by the Jewish and Polish organizations in North America, for their wartime heroism.
PROLOGUE: "This film is based on a true story. Przemysl, Poland. June 22, 1941. A city divided. Occupied by Germany on the far side of the river and Russia on this side."
The movie was shot mostly in Hradec Králové, Czechia. The opening scene on the bridge appears to be the "Prazský most" in Hradec Králové. A long shot from across the river.