The Molotov-Ribbentrop-Pact, which happened at the end of the movie, was in August 1939, not in the first half of the year, as portrayed in the movie.
In the movie Lavrenti Beria is announcing himself as the new chief of the NKVD forces in 1939. However he became Jeshovs successor already in November 1938, when Jeshov was arrested. However, as showed correctly, Jeshov was still a member a member of the central committee.
When Hans is dating the girl in his flat in 1936 he puts on a record of "You Are My Sunshine" by Bing Crosby, Voctor Young and his Orchestra, a record that was released in 1941. Also the song was written in 1937 and the first release in 1939 by the Pine Ridge Boys.
While spelling the word "Holly" from "Hollywood" in English Zeisig is pronouncing the letter Y not as "Why", even if he spells the other letters correctly in English.