6. The Blue Wizards
When the dwarf party are just leaving the Shire, Bilbo asks Gandalf about the other wizards. Its an interesting bit of exposition delivered naturally by the characters and helps set up the introduction of Radagast the Brown (more on him later). But it also doubles up as a little in-joke from Jackson to Tolkien-ites; even though the world-creating author wrote kid book The Hobbit, the more adult The Lord of the Rings and the frankly mammoth Silmarillion, documenting pretty much all major beings in Middle-Earth, he never once named the two blue wizards. So while its a great example of the humanity of Gandalf the Grey, its also a cheeky wink at one of the few oversights in Tolkiens vast world.