Not a lot. There was a mention in the first Hitchhikers series about "boldly splitting infinitives that had never been split before" and a mention in the Star Trek: Voyager episode "Threshold" about infinite speed meaning passing through every point in the Universe simultaneously, a crib from the Hitchhiker's Infinite Improbability Drive. But please don't watch that episode just to see it, it's one of the worst Star Trek episodes ever made.
Space
The "trilogy" of five books were published between 1979 and 1992.
The Hitch-Hiker's Guide to the Galaxy is 100% fact in the 42nd dimension.
Shynola
Approximately 15% of schools list The Hitchhiker's Guide to the Galaxy in their curriculum.
hitchhikers guide to the galaxy... it's a hilarious movie
2
Because it says so in the hitchhikers guide to the galaxy.
for leaving just before the world exploded in the hitchhikers guide to the galaxy
The brilliant book does not tell you, that's the point of the book!
Hit 4-2 in that order. It's from The Hitchhikers Guide to The Galaxy.
The Earth is destroyed to make way for a new hyperspace bypass.