Around the time of the incident in Sulzbach, that is supposed to take place when the train is in Germany, the train is running on the left side. It shows that the shooting was done in France, where trains run on the left side, but not in Germany, where they run on the right side.
The narration for the final scene says the train arrived at Wannsee, in the far west of Berlin. But the scene shows then driving from the east, down Unter Den Linden and into West Berlin. The British and American then ask passing jeeps for lifts to their respective bases which they would have driven past on the way from Wannsee, whilst the Russian turns around and drives back under the Brandenburg Gate into East Berlin.