Adywan, I found something that I have never noticed before but definitely needs to be fixed. It is after Han, Luke, and Leia arrive on Yavan, and Leia meets the commander and says "There is no time for sorrows, Commander. We have to process the information on this artoo unit."
After this little exchange it switched to R2 waddling around. His projector is on the wrong side of his dome. It looks like Lucas had the shot reversed during editing of the film. Anyways, here is a image of what I am talking about:

http://img180.imageshack.us/img180/4881/vlcsnap920124jg4.jpg

This happens at: 1 hr. 38 min. 51 sec. to about 1 hr. 38 min. 57 sec. on the NTSC 2004 DVD