The direction the sun sets changes from the beginning of the movie to the end. Initially the sun sets in the direction of the Croods' hunting grounds (two knuckle warning). But, they spend the majority of the movie heading towards a mountain in the opposite direction, which is where the sun sets for the remainder of the film.
The goof items below may give away important plot points.
When Grug finds Douglas near the end of the movie, he has Thunk's shell in his mouth from when Thunk threw it. When the scene cuts to the rest of the Croods blowing their shells for Grug, Thunk has the same shell even though Douglas should currently have it in his mouth.