Factual error: The temperature on earth is increasing more and more throughout the movie. People have been dropping dead left and right, but somehow all plant life is still greener than ever. All the moisture in the ground would be gone by now, so the leaves and grass should be dried up.
Factual error: In the beginning of the film, the camera shows the earth in front of the sun as the asteroid is heading for earth. The side of earth facing the asteroid is lit as if the sun were illuminating its surface, even though the sun is on the opposite side. It should be dark on this side.
