Question: After Alex finds his father and is driving back home, we see a scene from the hospital, where Lara (or another nurse?) is talking to Alex's mother and telling her that the Berlin Wall collapsed, and that Germany is united. But later, Alex's mother acts like she's unaware of this, and Alex himself also states that she never knew the truth. Why?
Question: Is the taxi driver the cosmonaut from Alex's youth? First he states that he's always mistaken for the cosmonaut, but then he tells Alex what's it like to be in space.
Answer: According to IMDb, Sigmund Jähn gave permission to be featured in the movie, but refused to play himself. It was very difficult to find an actor who looked like Jähn and spoke his typical dialect but after filming had begun, 'Wolfgang Becker' chose a Swiss actor. He was given complex make-up and was dubbed by another actor who came from Jähn's home region, the Vogtland.
Answer: Lara did indeed tell Alex's mother the truth. Realizing how much her son had done for her, she left him with the illusion that she never found out. The audience knows better.
Ioreth