The movie portrays Robert Koch as a lonely fighter for the progress of medicine. However in real life he had support by the bacteriologist Ferdinand Cohn from the Univeristy Breslau and his student and later pathologist Julius Cohnheim. Ferdinand Cohn gave him possibilities to produce experiments in their laboratories in Breslau in 1876. However Cohn was Jewish which is why he wasn't included as a character in this movie, made in Nazi Germany.
Koch's tuberculosis discovery happened in Berlin, not in Wollstein.
The straining method that Koch is using in the movie is created by Paul Ehrlich in the 1870s, based on the research of Ehrlich's cousin Carl Weigert.
In a scene set in 1881 in Berlin a man mentioned to Rudolf Virchow Heinrich Schliemann's new findings in Troja. Schliemann's Troja journey was in 1870-1873. His discussion about further exhumation in Troja with Rudolf Virchow was in 1878/79, earlier than the scene's setting.
While Koch's tuberculosis experiments with guinea pigs happened in Berlin, it happened in 1881, one year before he became councilor.
In the beginning of the movie Robert Koch is mid-30 years old. However he is portrayed by a 55-year-old Emil Jannings.