4. Why Aren't The Aliens Killed The Moment They Arrive If They're Allergic To Water? - Signs (2002)
The Plot Twist:Signs is a fairly basic but thoroughly entertaining movie about alien invasion, one infused with messages about religion, faith and baseball bat skills. The plot centres around a family who live on a farm as they comes up against alien invaders. When all hope seems lost, the twist reveals itself: the aliens are
allergic to water, in the sense that it kills them dead. Mankind eventually uses this knowledge to send the slimy bastards back to hell.
But, Uh... Though this twist is presumably inspired by a similar one glimpsed in H.G. Wells'
War of the Worlds, in which the alien invaders are doomed from arrival because of the bacteria in the air that we humans have evolved alongside for millions of years is lethal to them, it doesn't work. We can assume this is because H.G. Wells was a scientist, genius and scholar, and M. Night Shyamlan is M. Night Shyamalan. Firstly, if the aliens are allergic to water, the moisture and vapor in the air would have instantly affected them to a point where they couldn't get themselves locked in closet and recorded on camera at children's parties. They would have been screwed the moment they opened up their spaceship doors and stepped out. Secondly, why would a super advanced race of intelligent beings invade a planet that is 71% water? At least the Martians in
War of the Worlds had no way to know about the bacteria. Shymalan's aliens, on the other hand, are just dumb.