The original script by Ilya Tilkin has no literary source. Tilkin studied museum archives as well as the diaries of the Stalingrad Battle participants to write the script. Some parts of Vassily Grossman's "Life and Fate" were used for a few scenes.
The numbering of the German tanks is incorrect. For example, one tank has the number "716", which would make it the sixth tank in the first platoon in the seventh company. A German tank platoon had no more than five tanks, so it should actually end with "5".
Captain Kan mentions how he had once been invited to meet Field Marshal Paulus. The problem is the movie takes place in November 1942 and Paulus was only a General at that time. Hitler didn't promote him to Field Marshal until January 1943, thinking that a Field Marshal would never surrender...He was quite wrong about that, Paulus surrendered to the Russians the very next day.