Excellent answer which sums up most of my disappointments with the film.

I'll just add that the coming of Smaug is different in the film. All those homeless dwarves roaming the plain would have been a nice feast. In fact he dwarves inside were killed except for Thror and Thrain who mysteriously appeared on the mountain-side somewhat singed (setting up the later revelation of the secret passage). The Wood-Elves weren't there and didn't refuse to help. Also Thorin seemed to already have the map but not the key, and Balin would never question Thorin's actions in the presence of others.

Gandalf didn't use a moth to seek help (similar invention in LotR) but the Lord of the Eagles just happened to notice the commotion. Bilbo didn't make any heroic gestures of saving Thorin, or anyone else, during the goblin attack while they were in the trees.