The real Fritze Bollmann was born in 1852, not 1840, as suggested by the movie man in the first scene of the movie.
Fritze Bollmann is portrayed as a bachelor and had girlfriend Anni, as described in the original novel. In real life he was married to his wife Agnes and had 11 children, on which 3 only survived.
The melody that was sang to the "Fritze Bollmann" mocking song, "Zu Brandenburg uff'm Beetzsee" by Friedrich Hollerbaum, was released in 1906, 5 years after Bollmann's death. During lifetime the lyrics were written only as poems on postcards or were sang to made-up melodies.
In the movie Fritz Bollmann accepted his nickname "Fritze", while in real life it was used to mock him, which he disliked.