When the little girl crawls underneath the table to "steal" a cookie, the direction she is crawling from changes when the camera cuts to another angle.
During the World War One period and immediately after Adolf Hitler sported a traditional "handlebar"-type mustache. He adopted his trademark "comb" mustache shortly thereafter. In any event, all known photographs of Hitler as an adult show him with a mustache of some style.
When Max sees Adolf Hitler for the first time, he correctly calls him "Corporal", but the uniform Hitler is wearing has no rank insignia. German Army uniforms in both world wars displayed NCO ranks on the collar.
The film gives the impression that, among the other designs, Hitler designed the uniforms for the SS. In actuality, these were designed by Hugo Boss,
When Captain Mayr invites Adolf Hitler to speak in front of the Nationalist Socialist Party, he mentions that they number "500 men or so". The party actually only had around 50 members at this time and Hitler was given the number 555 when he became a member simply because the numbering system started at 500.
The film gives the impression that, among the other designs, Hitler designed the uniforms for the SS. In actuality, these were designed by Hugo Boss.
The family gathers to listen to the reports of the Armistice Agreement Terms (November 1918) on a radio. However, broadcasting in Germany didn't start until 1923 and was strictly experimental and limited before that.
The carpet in Max's house is an IKEA model from 2003.
The cigarette lighter used by Max is a type that didn't exist until after WWII.
During an early scene in the steelworks/gallery a worker is shown cutting up a locomotive for scrap. He is using an arc welder which was not in use until the second world war.
Hitler became a vegetarian 13 years later - in 1931.