Quote Originally Posted by memnarch
I wonder if that ever gets a mention in the movies or if it's a "read the tie-in comics to find out!" sort of thing.
Yes. C-3PO says "it's me C-3PO, I thought you might not recognize me because of the red arm." And then it's never brought up again in all three movies.

It's explained in some comic, because somebody has to clean after Abrams, I guess, and it wasn't going to be Johnson.

Here's hoping the Comic Irregulars do something with it.

Also, his leg is no longer silver and nobody comments on it, nor is it (to my knowledge) explained.