Austria is famous for its mountains and ski resorts. But certain parts of Austria are quite flat. And the border region between Bratislava and Vienna is VERY flat. No chance to cross the border over a mountain with a ski resort like shown in the movie, unless you take a 600km detour with three more border crossings.
After Bond returns to London (when he's completed his mission in Eastern Europe) there's an 'establishing' shot of a London street scene. Look closely at the placards behind the newspaper vendor. One of the placards says "BLAZING JEEP AT 2,000 FEET" - a reference to the Jeep on fire and going over a cliff in the pre-title sequence perhaps?