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.