Chess legend Garry Kasparov beat IBM computer Deep Blue four games to two in a match organized in 1996. A year later, he was man versus the machine again, accepting another challenge from the team behind the supercomputer. This second time around, IBM's competitor came out on top, beating Kasparov three-and-a-half games to two-and-a-half. After the loss Kasparov questioned whether Deep Blue's team had cheated in order to beat him, but in a fascinating new short documentary by FiveThirtyEight and ESPN, it's shown that the momentous victory — and the notorious 44th move that led to it — was actually the result of a computer error.