A couple of things I noticed when I watched through 2.5, I’m not sure if they’re errors or not:
at 36:15, the text on Luke’s screen seems to be “sliding” around on the screen. That is, the camera is shaking but the text remains at the same point in the frame. This could be something that was present in the theatrical and just a result of 1980 editing technology.
At 1:55:54, Both of C-3PO’s legs are gold, when both before and after this scene his right leg is silver. Again I don’t know if this is an error on Harmy’s part or the original editing team.