Bilbo tells the dwarves to "run back to the wood-elf clearing" while he fights a rearguard action against the Mirkwood spiders. However, the company has not yet met the wood-elves. When they reach the clearing, Bilbo notes that the wood-elves "had returned, armed for battle". This is the first time we see the wood-elves. There is a scene from the book which was clearly scripted but is missing from the animation, where the starving dwarves attempt to gate-crash a gathering of wood-elves in a clearing.
When Smaug attacks Lake-town a full moon is visible. However, as this is Durin's Day, the moon should be a thin crescent just past the phase of the new moon.
When Elrond reveals the moon runes on the dwarves' map, he reads the phrased as quoted directly from the book "Stand by the grey stone...", however the phrase shown is "Five feet high the door and three may walk abreast." This is a phrase which was not written in the moon runes.
When Bilbo finds the ring it's shown with an elaborate design on it. In the book the ring was plain and unadorned. Although when you put it in the fire, writing in the Black Speech appears.