"Designing the Enemy - Tripods and Aliens"

We hear from the following people in this approximately 14-minute bonus feature:

David Koepp - Screenwriter
Ryan Church - ILM Creature Design
Steven Spielberg - Director
Dennis Muren - Senior Visual Effects Coordinator
Kathleen Kennedy - Executive Producer
Simon Wells - Great grandson of Sci-Fi author H.G. Wells

Some interviewees discuss how the creatures were designed.
We learn that they wanted the aliens in War of the Worlds to be different from all prior bookcover artwork and the prior 1953 movie, but they still wanted to pay homage to the previous designs from past decades in some way.

The creature designers said they wanted the film aliens to have trilateral symmetry — unlike human beings, a bilaterally symmetrical species. The aliens had three limbs, with three toes/fingers. Their legs were also had two knees instead of one (as humans do). The creature designers settled on only two eyes, however.

Similarly, their Tripod 'walkers' were designed to be three-legged, with three metal toes, and three white lights horizontally arrayed in the 'head' portion.

A memorable quote from Steven Spielberg in this bonus feature: "Well, Martians is not mentioned in my film because my aliens don't come from Mars." Spielberg is referring to both the 1938 radio play and the original H.G. Wells story, both of which featured alien invaders from Mars — a planet that was still a mysterious red ball in the sky, as far as previous generations were concerned. Mars would not be explored by Man's robotic space probes until the 1970's.

Extra link #1) "Full Movie Review of 'War of the Worlds' (2005)"

Extra link #2) "Differences between 1953 and 2005 films of War of the Worlds"