The British Army, that was supporting the Prussian Army in the 7-year-war, is not mentioned in the movie at all. However this could be part of the propaganda, since the movie was made during WW2, where Britain was the enemy of Germany and therefore it wouldn't fit if they would be portrayed positively in this movie.
In the movie the battle of Kunersdorf is lost due to the cowardliness of the tired Prussian soldiers. In real life it was lost due to an exaggerating strategy of King Frederic. Furthermore the movie shows the Habsburg army of Austria as the only opponent in this battle. But Austria were fighting with Russia together, which was not shown in the scenes at all. This was only mentioned briefly in the dialogue later by Prince Heinrich senior.
In the movie the characters ensign Niehoff and sergeant Treskow talk to each other as friends. However while Niehoff is a simple under-official Treskow is an civil official, Friendships between such different society levels were very rare in the 18th century.
At the Kunersdorf-battle the Austrian artillery is wearing white uniforms instead of brown uniform as it was in real life.
The portrayal of Price Heinrich junior is incorrect in this movie. In 1759, when he visited his uncle, King Frederik II, at the war, he was 12 but in the movie he is portrayed by a 17-year-old actor. Also he died in 1767, four years after the war. In the movie however he died in 1760-61.
The eagle on the Prussian flag at the beginning of the movie was used in Prussia after WW1, about 200 years after Frederic the Great.
Frederic the Great is celebrating his 50th birthday shortly before the invasion of Schwednitz, which was in October 1762. However his birthday was on the 24th January. But the year (1712) is correct.
During the movie, set in the 7-year-war, Frederic the Great is called "King of Prussia". This is a title he received in 1772, 9 years after the end of the war. Until then he was King IN Prussia.
In the German original version of the movie a general is using the term "Hiobsbotschaft" (jeremiad). This term was not used until the 19th century. Earlier it was called "Hiobspost", which however has the same meaning.
In the scenes set in Vienna in the 1760s the Gloriette of Schönbrunn Castle can be seen. However this was built in 1775, 12 years after the 7-year-war.
General Sachar Tschernyschow mentioned that Czar Peter III was killed. However the reason for Czar Peter III's death was not known back then. Even today it is not clear how he died in 1762.