War of the Worlds is an excellent example of many disciplines in filmic special and practical effects, and is a tent-pole in the science-fiction genre. Byron Haskins combined scale-models, life-size props, pyrotechnics, and film layering methods pioneered by B-movie directors such as Ed Wood in a high-profile film. Haskins was operating at a significantly higher budget than his exploitation-era peers. Perhaps the largest advantage Haskins had was Technicolor, allowing him to utilize color. This allowed him to use ominous reds and looming green hues to further enhance the “alien-ness” of the Martians and their war machines.
The use of miniatures in War of the Worlds is well executed, especially for the time, rivaling the work of even Ray Harryhausen. Actors are never seen interacting directly with a model; human interaction with up-scaled stop-motion models tends to break the realism of the fictional entity, as seen in any Harryhausen film, or even Star Wars: Return of the Jedi and RoboCop. Any interaction between a living actor and the space crafts are through life-sized parts of the machines, such as the periscopes. This allows the crafts to keep their imposing visage.
In the novel, the heat ray is a terrifying and potent weapon, partly due to its quite, invisible nature. To have the effect transfer to film, however, would require bombastic use of both light and sound. Films of pyrotechnical displays were layered over the film of the movie proper. This technique was far from new at the time, but combined with deft usage of onsite pyrotechnics (something far-beyond what most B-movies could afford) and ashy set-dressing help create the imposing weapon. Sound was also a key component; jarring whines and wailings assault the viewers’ ears. This incarnation of the classic heat ray is one of the core examples of H. G. Well’s in popular fiction.