If you really want to fix a Vader pantomime, look at the discussion between Tarkin and Vader about Leia's lie. He is flailing his arms around like he's trying to sign the whole thing to Tarkin. Vader stops talking at one point and then points at Tarkin, which should have lined up with him stopping. It's always been that way. But if I was in the room when they were doing all the other changes Lucas was doing to the films (not the stupid ones), I would have told him to fix this. It was a dubbing mistake and should have been corrected in 1977.