ceebeegee | I like this

From a review of War of the Worlds:

But there's also an intellectual coherence to the film. What seems to hold it together is the concentration on blood. This extends from the initial idea of Mars as the "Red Planet" to the blood ties between Ray and his kids that turn out to be what gives them strength. It turns out further that the invaders have come to Earth for, specifically, blood; they are vampires who need our plasma to live. When they are done with their prey, they leave a blood residue, and in one scene, a red landscape is seen stretching to horizon, as if all humanity had been rendered.

Spielberg is only marginally interested in what eventually overcomes the invaders. He cares more about human adhesion, the stuff that binds us together and that, it seems, makes us human to begin with, unlike the cold, distant intellects of Mars. The idea seems to be: That was something they couldn't relate to, and in the end, that, as much as anything, dooms them. Our blood was thicker than theirs.

I did notice all the red and figure it was about Mars, even though the movie never says that's where they're from. But it wasn't just a visual theme, but an emotional one as well. Neat.