When being in Russia Trenck said that he needs to go back to Danzig because his mother died. However his mother Maria Charlotte von Derschau died in 1747. In real life Trenck went to Russia in 1749 and arrived in Danzig only in 1753 for her funeral.
In the last part of the movie Trenck is portrayed as a single guy missing his love. However he was already married in 1765 to Maria Elisabeth de Broe zu Dipenbendt, the daughter of the Mayor of Aachen.
Maria Theresia of Austria was, despite being titled as such due to marriage, never officially an empress of Austria, as she was never crowned. She was an Arch-Duchess of Auststria and Queen of Hungary and Bohemia.
Friedrich von der Trenck and Princess Amalie of Prussia first met on the wedding of her sister Luise Ulrike in 1744, not after a talk with the king before the war in the early 1740s.
While Friedrich von der Trenck and Amalie of Prussia were very close it is not secure and not proven that they had an affair.
When Empress Elisabeth of Russia enters the hall the anthem "Bizhe Zarya khrani" by Alexej Lvov can be heard. This melody was written in 1833 and was used as an anthem from 1833-1917, while Elisabeth was ruling from 1741-1762.
Skull and Bones as a symbol was not used in the military in Europe until the late 1700s while the scene is set in 1753.
King Friedrich Wilhelm II mentioned that Trenck and Amalie haven't seen each other for 20 years. However the scene is set in 1786 and the last time they saw each other was in the 1750s, which would make it over 30 years.