@jury Good question. The only key Hobbit inaccuracy I could come up with is that while Azog does behead Thorin’s grandfather, he’s dead by the time of Bilbo’s expedition. Everything else is pretty well sourced.
@jury Seems like little was just "made up".
Some was from other works (The Appendices from LOTR), and a small amount was not referenced anywhere (Radagast's scenes, for the most part).
But I actually liked Radagast's role in the film. :)