Trivia: While he enjoyed the finished film, star Bill Paxton admitted he wished "Twister" was a bit darker and edgier. For a while around 2010, he tried to get a sequel off the ground to deliver this more intense vision, and he was even interested in potentially directing the follow-up. Little is known about what the sequel would have been about, although Paxton hinted he wanted to utilize 3D filming techniques (which had been re-popularized by James Cameron's "Avatar") to really put the audience into the tornado chases. Unfortunately, the sequel never came together.
Trivia: According to the Special Effects documentary, the sound of the tornado was produced by recording a camel's moan and digitally slowing it down.
Suggested correction: The scale back then was based on the size of the tornado, it's only more recently it is based on damage. So during the time of the movie, the scale was being used correctly for size not damage.
The Fujita scale was introduced in 1971 and was in use during the 90's when this film came out. The Fujita scale measured the damage caused by a tornado to man-made structures after ground or aerial surveys, it was not a measurement of tornado size (an F5 tornado is a tornado that's rated on the Fujita scale). It is true the Fujita scale was replaced by the enhanced Fujita scale in 2007, but that was only to align the ratings to the damage better, it did not change rating tornadoes from size to destructive powers.
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