You might remember Kurt Gödel. He was last seen on io9 proving the existence of God, at least in theory. Legend has it he also found an odd clause in the Constitution which proves that the United States could be legally made a dictatorship. And he told it to immigration officers.
Kurt Gödel was born in 1906 in Austria. Whether he was born a philosophical genius, a deep eccentric, or an outspoken political innocent, or whether he simply became all of those things later in life is up for debate. What isn't up for debate is that none of those things were assets when the Nazis rolled into Austria. Gödel,and many other extraordinarily intelligent minds decamped for America. Some were more welcomed than others. Albert Einstein didn't have a problem getting in, but Gödel's citizenship was still in question towards the end of the 1940s.
In order to get citizenship, Gödel had to pass various tests, go through an interview, and have a couple people vouching for his character. One of those people was Albert Einstein, so Gödel was made a citizen. After the citizenship was confirmed, Einstein talked about how Gödel's interview went. The officer conducting the interview mentioned how wonderful it was that the United States was not and would never become a dictatorship. Gödel, obviously pleased that the subject was raised, said that actually it was perfectly possible for the US to become a dictatorship. In fact, he said, he had discovered a loophole in the Constitution that made the entire thing quite likely.
It was at this point that Einstein broke in. Gödel wasn't being a cynic; if anything he was whole-heartedly embracing his new country and trying to point out something that might cause problems. He didn't know that that's the kind of thing that one does only when the ink is dry and the oaths sworn. He was made a citizen despite his attempts to show how the central document of American government was a road to dictatorship.
The story has attained the status as an urban legend. Neither Einstein nor Gödel ever revealed what the problem with the Constitution was, or how it could be logically exploited. Over there years, many have made guesses. Generally it's thought to be Article V, and the power to amend the Constitution might result in the Constitution's legal dismantling. Article V might itself be amended to make amending easier, and the rest of the changes to the Constitution could flow from there. What do you think?
[Via A Contradiction in the U.S. Constitution?, Godel's Loophole]