4. The Aliens in Signs
M.Night Shyamalan tried his hand at Aliens in 2002's Mel Gibson flick,
Signs, and achieved mixed results. The first hour or so of the film is extremely creepy. The crop circles, the signals on the radio, the atmosphere of creeping dread, the strange silences, they all added up to a truly enthralling and engaging alien film. Unfortunately this sci-fi film let's itself down in the third act when, after revealing the fairly creepy aliens to it's audience and establishing a climactic ending, it has our protagonists defeat their invaders with water. Yep, water. Quite frankly, it's pretty difficult to be scared or threatened by something that dies when it comes in contact with water, and is so damn stupid that it decided to invade a planet that is 70% toxic to their species. Can you not see the Pacific Ocean from space?