While filming at Big Water in Utah, the crew accidentally discovered a 60-foot-long sauropod dinosaur skeleton. The state's land management bureau took over.
The rights to the novels have since reverted back to the Edgar Rice Burroughs estate, which is still game to try to turn the books into a successful movie franchise.
"A Princess of Mars" was originally published as "Under the Moons of Mars" by Norman Bean (Edgar Rice Burroughs' pseudonym) in The All-Story (six pulp magazine issues February-July, 1912). Burroughs was originally afraid that he might be ridiculed for writing such a tale, so he decided to use a pen name. The pseudonym was supposed to be a pun ("Normal Bean", as in "I'm a normal being") to reassure people, but the man who typeset the text thought it was a mistake, so he changed it to "Norman". However, Burroughs' fears turned out to be unfounded: the story and its sequels, collectively known as the "Barsoom series", were almost as popular (and arguably more influential) as those of his most famous creation, Tarzan.
The film probably holds the record for the longest time in "development hell": 79 years. Preproduction first started in 1931, when Robert Clampett, director of 'Looney Tunes', approached author Edgar Rice Burroughs to make an animated feature out of the first book in the series, "A Princess of Mars." Had plans gone through, 'John Carter' could have become America's first animated feature, beating Walt Disney's Blanche-Neige et les Sept Nains (1937). It finally left development hell in January 2010, when filming officially started in London.
For each of the super jumps that Taylor Kitsch performed, he was attached to a harness that allowed him to free-fall at a speed of 80 mph. Kitsch apparently found it unpleasant.