When Kurt started the painting of him and Elisabeth, there were no grid lines. When he was almost done with the painting, grid lines are now visible.
When Kurt is painting the sign, he stops the O at about 2:00, if it were a clock dial, when his colleague makes the freehand comment. When Kurt resumes painting, it is from 12:00, not 2:00,
When Elisabeth tells Kurt about the room for rent, he has scratches on his face. A couple of days later on Monday when he goes to rent the room, his face has no scratches.
At one point Carl Seeband mentions that Mozart was dead by the time he was 30. This is incorrect; Mozart was 35 when he died. (He could have been lying to try to convince Kurt to give up Art).
Physicians and psychiatrists, and at the same time SS officers at the Zentraldienststelle T4 meeting in 1940 wear black Allgemeine-SS uniforms, while during the war the entire SS was uniformed in field grey uniforms--without swastika armbands.
The sign on the pillar on the left to the stair in the Düsseldorf women's hospital says "Chirugie" where it correctly should be "Chirurgie."
In the newspaper front page announcing the building of the Berlin Wall, during the first meeting between Verten and Kurt, one of the headlines reads "Jetzt muss der Westen handeln!". This is the modern spelling of the verb; in 1961, well before the reform, it was "muß".
During the air raid on Dresden on February 13-14, 1945, there must have been snow (because of the cold winter at the time) when the hero watched the Avro Lancaster bombers flying--and most importantly, Richter lived in Reichenau (now Bogatynia), located 100 km east of Dresden, so he couldn't watch the incoming planes.