20 Things You Didn't Know About Star Wars: Revenge Of The Sith
17. C-3PO's Armour Created A Huge Problem For VFX Artists
Though the prequels took increasing advantage of ground-breaking blue-and-green screen technology to give George Lucas maximum control over the production, this also created a major technical issue where the character of C-3PO (Anthony Daniels) was concerned.
Given the highly reflective nature of his iconic gold armour, the blue/green sets would be blatantly visible in its' reflections, requiring the VFX team to manually repaint Threepio's armour in post-production frame-by-frame.
As much as the emerging tech allowed Lucas to heavily tinker around with the prequels in post, it also created this migraine-inducing problem for the poor VFX team, who no doubt cursed any moment where C-3PO appeared practically in a scene.