At the beginning of The Prestige, Cutter tells the court that he caught Borden backstage watching Angier drown. But at the end of the movie, it's clear that Borden was desperately trying to smash the glass to get Angier out, and in fact Cutter stops him from delivering further blows to the glass.
Is this just a simple case of faulty eyewitness testimony? I can think of no other reasonable explanation for Cutter to say that Borden watched Angier drown.