As shown correctly Gurtav Hartmann did his carriage drive from Berlin to Paris in 1928. However Charles Lindbergh's famous arrival in Paris from his first Atlantic flight was in May 1927, one year before the plot's setting. And unlike in the movie Hartmann was received with cheers in Paris.
The radio broadcaster said that Gustav Hartmann is 62 years old. The movie is set in 1928 when Hartmann was 68 and arrived in Paris at his 69th birthday.
In the movie Gustav Hartmann is portrayed as a poor man who has depths and hated cars. This is based on a famous myth about Hartmann. In real life he was very rich and even owned two cars, a "Mercedes" and a "Dürkopp Adler".
Gustav Hartmann's horse was called "Grasmus" (originally "Erasmus"), not Lotte, as in the movie.