I'm also in awe of the nerve it took to get the balloon off the ground- especially after their earlier failures- and take to the air with their wives and children, one of whom was only two years old. This part of the film is extremely tense, as the balloon develops a hole and it's not clear if they'll make it over the wall before their fuel runs out. Again, this was true to life: the flame was too high in the balloon and burned a hole in it. Also, as depicted in the movie, the gondola consisted of a floor with some flimsy railings made of strung clothesline. The families, clinging to that frail gondola, floated as high as 2,500 meters in a balloon which was dangerously leaking, constantly worried that they'd be spotted and shot down by the Stasi. As it turns out, they were detected but were too high at that point to be stopped.
When the balloon comes to rest, the Strelzyks and Wetzels don't know at first which side of the wall they're on, and it's cathartic to watch their fear and dread turn to unbelievable joy when they realize that they've reached West Germany and freedom.