The movie shows the end phase of life in Auschwitz and the forced death march as the camp is evacuated. Salamo Arouch is sent to work in the Sonderkomando in the crematorium where suddenly he witnesses the uprising and destruction of what is clearly crematorium II or III. In reality, the uprising occurred in October 1944, months before the evacuation. The SS dismantled the crematoriums over the preceding months and the forced death march evacuations occurred in late January. (In addition, the evacuation occurred in the middle of winter, the movie shows a nice sunny day, where in reality there would have been snow on the ground.)
In the movie, Salamo Arouch was depicted as having married "Allegra" shortly before being sent to Auschwitz. In reality, Arouch met her for the first time after they had both been liberated from Auschwitz in 1945 and were subsequently married. Furthermore, "Allegra" was a name used by the writers for artistic reasons, his wife's real name was Marta Yechiel.
During the movie, Arouch was rewarded for his boxing victories with a reassignment to the factory, which was considered easier work, was inside and provided more food for him. According to the real life Arouch, he was actually assigned to the camp's kitchen. He was able to take advantage of this work assignment by secretly procuring food from the kitchen for himself and his friend.