The easiest movie to make has to be a movie where you dont need to explain anything, and that is exactly what this movie does. No visible monsters, no explanation why they arrived, no explanation how they do stuff or why people goes mental, no explanation why some people can survive the monsters, no explanation why the survivors are happy, etc, etc... People are also going insane when looking, even when the monsters arent there... This was just rubbish, and I cant understand why people arent more critical.