 The person responsible for extras casting was Jewish and was casting  a lot of his friends and relatives in tiny parts. As a result, when  the military consultant (from the KGB) saw the chosen actors, he  said that most of the guards at Nazi headquarters looked like  soldiers of Israeli army, not elite SS soldiers, and demanded that  they change them to more appropriate looking actors. As a result,  the roles of SS guards were played by military cadets of the  frontier