Juggernaut (1974)

Character mistake: Juggernaut says to cut the blue wire to defuse the bomb. At the last moment, Fallon decides he's lying and so cuts the red wire and successfully defuses the bomb. But he failed to tell the other defusers this before he cut it! If he had guessed wrong and the bomb had exploded, the other defusers would have assumed he had cut the blue wire and so would also have cut the red wire and also exploded their bombs (or after the next bomb had gone off, they would have assumed the wire-color was random).