At the end of the battle against Jabba and his henchmen, which was set in (what appears to be) a real desert, the two droids are lifted out of the sand, feet first, against a very fake looking backdrop.
Given the attention to detail throughout the original trilogy, this seems to have been a strange decision.
Was it due to time constraints, budget or something else? I'm curious to know if there is an on-set 'story' behind this scene.
After adding pictures: on every viewing of ROTJ, the backdrop appears "unreal", but after adding the above picture, it might be more that the sand in the foreground is oddly lit? At any rate - it looks bizarre, as if they forgot to film it whilst on location.