Anna and Martin are seen wearing their wedding rings on their left hands. In Germany and Austria however, people wear them on their right hands.
The BM sailing boat used by Lotte and David has sails with transparent plastic windows. These did not exist before the war.
In the scene where Anna is dancing with the soldiers in early 1940, a couple of them are seen wearing the close combat bar over the left breast pocket on their uniforms. The award was instituted in November 1942.