There are actually about 79,000 Americans still MIA from WWII, however this includes ALL theaters of war and those (a large number) lost at sea. The number for those who may have been trapped behind the Soviet lines after the war are small and by no means approach 50,000 or 40,000. However, if spanalot meant there were 50,000 or 40,000 of Stepan Bandera's allies he would be closer to the truth since a large number of Germans captured remained in camps in the Soviet Union until long after the end.
Patton has always been a hero of mine, as he saved my Dad and thousands of other troops. My Dad was a "Battered Bastard of Bastogne", 101st Airborne.
When Von Paulus surrendered at Stalingrad his forces contained about 110,000 men. 400,000 had been killed by the Soviets. Occasionally the History Channel interviews survivors of this battle.