The estate of H.G. Wells was so pleased with the final production that it offered George Pal his choice of any other of Wells' properties. Pal chose L'uomo che visse nel futuro (1960).
The Martian war machines were originally going to be walking tripods as they were depicted in H.G. Wells' novel, but George Pal didn't know how a tripod would walk and instead went with the flying machines.
Most of the soldiers in the movie aren't actors; they're actual National Guard troops going through real maneuvers.
The Martian war machines had about twenty wires running to each one. Some were for suspension and maneuvering, while others carried power to the various lights and mechanisms. This was produced before there were lightweight circuits and sophisticated radio controls.
Filming was halted briefly, two days into filming, when Paramount discovered that its filming rights of the novel were only for a silent version. It was quickly resolved through the kind permission of H.G. Wells' estate.