Plot hole: If the gasoline in fuel lines and tanks is reaching flash point and exploding, there should not be so many cars just sitting around. Surely all of those vehicles' tanks are not dry.
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.
Character mistake: Throughout most of the movie, many of the characters are seen wearing dark, heavy clothes such as long pants, sweatshirts, etc. Wearing warm clothing puts them at a greater risk of suffering heat stroke and dying more quickly, than if they wore light-colored, cooler materials.
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.
