WARNING! LAST IMAGE CONTAINS A BOOK 3 FINALE SPOILER.
I don’t know if most people are aware that Amazon has free “The Spirit of an Episode” videos for each episode of Book 3, but if it’s not common knowledge, people should check them out. They give a lot of interesting facts about the production and show quite a few neat references!
One needs to download “Silverlight” to be able to watch them, but it’s a quick process that one can do right on the site.
Here’s a link to the first episode if anyone cares.
And here is a post with most of the background references that were shown in the videos.