I had read (thanks, MetaFilter!) that Ron Moore does a podcast commentary for each episode, and have finally gotten around to listening to them. They are awesome! It’s Ron and his wife (who is the costume designer on the show) sitting around watching the episode and talking about making it. I’ve been searching for a good link to the podcast, and all I can come up with an iTunes link. I have an Android phone and found the podcast pretty easily just by searching for it using the BeyondPod app, so it should be pretty easy to find if you don’t use iTunes.
Also, the aforementioned costume designer, Terry Dresbach, has an awesome blog where she talks a lot about the costumes for the show. It’s fascinating. I can’t get over how much work it is to make a show like this, and in another life (a life where I learned to sew and had some measure of artistic talent), I would love to be a costume person for historical shows/movies. As a kid I used to sit for hours with my grandparents’ World Book encyclopedias poring over the details of historic times and different places, and the clothes/hair/makeup has always fascinated me. I was, clearly, a gigantic nerd.