Actually I wactched it again the other day, and there's something that could be called a mistake, or maybe jsut an inconsistency. When Vader and Obi-Wan meet on the Death Star in the original, Vader's saber is already lit up (which I liked, in that he really was waiting for him right there), in Revisited, it's not on, and he lights it up as he walks towards him. This is grand, but the noise his saber makes as it lights up is not the noise Vader's saber makes in ESB and ROTJ, it's the standard "woosh" of Luke and Obi-Wan's sabers, as opposed to the higher and sharper ESB/ROTJ one.
In the prequels, all the Jedi sabers use the "woosh" sound, all the Sith sabers use the Vader one. I guess this has offically been designated the "Jedi Lightsaber Sound" and "Sith Lightsaber Sound", but I, for one, don't welcome anything from the prequels, so that is moot to me. What isn't moot, is that Vader's sounds different in ESB and ROTJ, and since it was not seen lighting up in the original ANH, I'd call it a legitimate inconsistency.
Pointless complaining now of course, since Adywan is long finished on ANH:R, but it's one of the very few things that bugs me in the edit, so I thought I'd say it.