While Sally and Kolya are being transported on a moving train, a German guard is bringing them food. In the camp hierarchy, German guards seldom interacted with prisoners, instead having other prisoners undertake menial tasks of serving food. Prisoners were seldom fed during transport as these cattle-wagons were not inter-connected and most likely locked from outside.
Only prisoners admitted to the Auschwitz concentration camp complex had tattoos placed on their left forearms, but this story doesn't take place there and no other camps employed tattooing. Increasingly, movies, paintings, and other media have used the tattooed arm as a "symbol" of the camps or even the Holocaust itself - despite the historical error. There were two series: A ( up until 20,000 - July 30, 1944), and the B series - starting shortly thereafter. Those selected for the gas chambers after arriving were not included. These numbers were meant to be used as an identification marker at the time of death of the prisoner.