3. Signs
Signs is a movie that showed what would happen in the event of an alien invasion. They come to Earth, cause a little mayhem and destruction, and… it ends almost as abruptly as the invasion began. It turns out that the aliens’ weakness is good ol’ H2O, which raises the question: how come they tried to invade a planet that’s more than 70% water? Hell, there’s even water in the air! And they weren’t wearing anti-water suits either, so they were exposed to water from the get-go.