Ernst Renz was never a leader of a circus groups until he arrived with his mentor Rudolf Brilloff in the 1840s in Berlin and started their headquarters.
The opening of Renz' circus theater is showing during snowy winter weather. However the opening actually was on October 20th 1850, not in winter.
Ernst Renz is portrayed as a single guy who is interested in his performer Bettina, whom he later describes as his fiancee. In real life he was already married to the dutch circus artist Antonette Aelmans since 1842, with whom he had seven children from 1844 till 1851.
When dictating his will Renz introduces himself as "Ernst Renz". In a will usually the full name has to be mentioned, which, in this case, would have been "Ernst Jakob Renz".
The circus of Louis Dejean didn't arrive in Berlin until 1850. At that time Circus Renz, until 1850 under the name "Circus Olympic", was already an established and successful circus in Berlin.
In the movie "Circus Renz" had its name from the very beginning, as seen on the main sign in the tent during the performance. In real life it was found in the 1940s as "Circus Olympic" and didn't get its known name until 1850.
The water pantomime performance didn't start until 1890, while in the movie it appeared in the 1850s.
The first advertising column by Ernst Litfaß, also known as "Litfasssäule" was thought of in 1854 and was first built in 1855, way after Louis Dejean left Berlin in 1852.