Back to eyebrows: would you believe they actually acknowledge this on starwars.com on the episode page?!
“Although the final cut of Return Of The Jedi has an eyebrow-less unhelmeted Darth Vader, to better read in animation, the animation model has the dark brow visible through the cracked helmet.”!
I just watched the finale, and was so excited about the eyebrows that the first thing I did was open up this thread and search for it. Maybe these dumbass changes will slowly slip from the grip of canon.