Captain Grivtsov is sent to Stalag 345, but that camp was in Ukraine and not Belorussia, and it was closed by the time the story takes place anyway. The only Stalag camp in use in the area by the time in question was Stalag 373, but Grivtsov, being an officer, should have been sent to the nearby Oflag.
The main plot device, the deployment of a V-2 rocket to hit Moscow, fails because of several factors. It is implied that the story takes place during the summer of 1943. The V-2 was still undergoing tests, and the first offensive use was in September, 1944, a year after the appearance in the movie. Besides, with a range of 320 km, it wouldn't have been able to reach Moscow, which is about 620 km from the Bobruisk area.
During the air combat scene, a German fighter plane is identified as a "Messerschmitt". The plane in the scene is anything but - the cockpit canopy, the tail section, and the overall silhouette are wrong. The plane have more similarities with the Heinkel He-100, but that aircraft didn't see service on the Eastern Front.