What Could Have Been: Ray Harryhausen apparently always wanted to take on the story, but never got the chance to do so.
The mass panic associated with the radio broadcast? Fake. Most people would have reacted as most probably would today: call the police or friends and find out, and while the station had unusually high calls, they were all just calling for information, praising or complaining about a particular show. And the listening audience size was six million, there were bound to be people doing stupid things anyway (though it's likely anyone that thought it was real simply tuned in late, only heard "invasion" and "poison gas" and assumed the Nazis were invading).