In the late 1970s the UK's Anglia Television ran a respected weekly documentary series: Science Report. But when the show was cancelled in 1977, the producers decided to channel Orson Welles in their final episode. The result was Alternative 3. Over the course of the hour, the audience would learn that a Science Report investigation into the UK "brain drain" had uncovered shocking revelations: man-made pollution had resulted in catastrophic climate change, the Earth would soon be rendered uninhabitable, and a secret American / Soviet joint plan was in place to establish colonies on the Moon and Mars. The show ended with footage of a US/Soviet Mars landing from May 22, 1962. After Alternative 3 aired, thousands of panicked viewers phoned the production company and demanded to know how long they had left to change planets. [more inside]
No one would have believed in the middle of the 20th Century that human affairs were being watched keenly and closely by intelligences greater than Man's...
WNYC's Radiolab took a look into Orson Welles' 1938 radio production of H.G. Wells' novel The War of the Worlds, which caused mass panic in the United States when listeners mistook a radio drama for actual reporting. They then explored the question of whether such hysteria could be recreated in a similar way, recounting stories from Quito, Ecuador in 1949 and Buffalo, New York in 1968. (There was one other attempt in Santiago, Chile in 1944 which is not mentioned in the Radiolab synopsis.)
Edison's Conquest of Mars! Garrett P. Serviss' unofficial, 1898 sequel to War of the Worlds, featuring Thomas Edison and Lord Kelvin as the heroes. It seems this book originated the space battle and the ray-gun, not to mention the aliens-built-the-pyramids plot. Sounds like a blast.