The Rosetta Stone is written in three scripts because when it was written, there were three scripts being used in Egypt. The first was hieroglyphic which was the script used for important or religious documents. Detail of hieroglyphic and demotic script on the Rosetta Stone.
The Texas Chainsaw Massacre never happened in real life. The filmmakers just wanted people to think it was a true story, so more people would go see the movie. It was also a bit of a joke on their part, to see if people would believe it was real.
The Outlaw Josey Wales was inspired by a 1972 novel by Forrest Carter, and was originally titled The Rebel Outlaw: Josey Wales and later retitled Gone to Texas.