-- ANH
In the original, Vader's saber is flat white after he kills Obi-Wan and Luke shoots the control of a door to keep Vader from entering the fight on the Death Star. I think the '04 edition corrected that. Incidental but there you go. It's fine the way it was though.
-- ESB
The expanded approach to Cloud City is okay, with the all the CG buildings and whatnot. It's fine the way it was though.
-- ROTJ
Uh, hmm...