Ok, stupid but genuine question, in the outdoor Tatooine shots in IV, for some reason the lower right panel on R2’s back is painted uniformly grey. Any point? Production goof? It seems intentional and I don’t think that body was re-purposed at any time to be another droid so what gives? It goes away for pretty much every indoor shot and Mos Eisley, so maybe my sleep-deprived brain is going crazy…
It may be a production goof, since the Tatooine bits were shot before the rest of the film.