This movie is based on a real-life event that occurred about 10 years ago.
In a few scenes while Alvin is driving the lawn mower across Iowa, you can see he has the old-fashioned blue license plates which were in use up until about three or four years ago on the back of his trailer. Yet during the scene where the woman hits the deer, her car has the new issue license plates. Remember I said above that the real-life event took place about 10 years ago, so the plates on her car should be blue too.
Some other small slipups:
-In the scene where Alvin is cooking the deermeat, and the camera shifts to show deer standing all around him, you can very plainly see that they are all fake.
-There are a couple slipups that would occur whenever the camera pans to show the "star field". First, whenever the camera would look at the stars (Which were obviously CG), if you looked very carefully, you could see them moving towards the camera (Probably be easier to see on fast forward) I'm not just talking about the final one before the end of the movie, Im talking about all of them. Second, there was one scene where the camera panned up to look at the "stars", and the ones closer moved faster than the ones farther away (Like holding one finger close to your face, one far away, and moving your head back and forth. The fingers seem to move side to side at different speeds). But stars are so far away that this shouldn't have occurred.