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In the first scene depicting the Polish officers in the Soviet POW camp, the subtitles in both Polish and English incorrectly give the location of the camp as "Kozielsk", USSR. This is a mistake. Kozielsk is a small village in Poland, but the historical camp where the Polish POWs were sent by the Soviets was outside the town of Kozelsk in Kozelsky Oblast, USSR.
When Soviets are about to execute the General, there is a portrait of Joseph Stalin on the back wall. Stalin on the portrait has the uniform with shoulder straps of the Marshal of Soviet Union. Soviets begun to use shoulder straps in 1943 and Stalin did not had any military rank during events of Katyn massacre. He became Marshal in 1943 and Generalissimus in 1945.