A great escape, an epic swordfight, and a funny (if thought-provoking) conclusion.
The fall of the Soviet Union can best be explained in two words: human nature. Humans are generally good-natured, but tend to be greedy, lazy slobs. In a perfect world, communism (and other utopian ideals) would work - but ours isn't a perfect world. Democracy and capitalism (with a reasonable degree or regulation) are the governmental and economic systems that best suit a species that values free will. Anything else falls short in some way or another.