Live ammunition was used during filming. In interviews, Aleksey Kravchenko has described bullets passing 10 centimeters above his head.
The Nazi German SS Major Sturmbannfuhrer's pet is a Red Slender Loris, a species similar to a lemur.
Many of the uniforms are originals.
Some of the German soldiers use Russian weapons. They were less likely to jam, and could work at lower temperatures than many German-made guns.
The director planned to have Aleksey Kravchenko hypnotized by a psychotherapist during the most dreadful and violent scenes so that they wouldn't affect his young mind. However, turned out not to be susceptible to hypnosis and had to pretend all the way.