Luxembourg has an airport and Liechtenstein does not! It might pay to say "Has German as an official language" because Luxembourg actually has three, one of which is German. Since I've visited Vaduz, and it's on the edge of the Rhine River, it's hard to work out if that counts as flowing "through" it.
Yes, the river question is dubious. The Rhine river is right next to Vaduz, and even though you want to not count it, there is the Giessen river that flows right through the city.
Also, question #14, "double landlocked" means "landlocked by two landlocked countries", not just two countries. Uzbekistan is a double landlocked country, because all its neighbours are landlocked, but it has 5 of them, not just 2.
Also, question #14, "double landlocked" means "landlocked by two landlocked countries", not just two countries. Uzbekistan is a double landlocked country, because all its neighbours are landlocked, but it has 5 of them, not just 2.