1. The Hitchhiker's Guide to the Galaxy was inspired by Douglas Adams' own experiences hitchhiking, and the idea for the book occurred to him while traveling from London to Istanbul.
2. The Hitchhiker's Guide to the Galaxy has inspired a full length feature film, several sequels, a computer game, a TV series, comic books, and began life as a radio story.
3. Ford Prefect believed that his name would help disguise him during his time on earth, because he thought that cars were the dominant form of life on the planet.
4. Zaphod Beeblebrox is Ford Prefect’s semi-half cousin with whom he shares three of the same mothers.
5. Towel Day is an annual celebration on the 25th of May where fans of the series carry towels in tribute to Douglas Adams.
6. Adams did not have a general plot outline for any of the novels and wrote them as he went. This is what lends the book its meandering long-winded quality.
7. According to the book, dolphins are the second most intelligent creatures after mice and tried to warn us of the destruction of earth. We misinterpreted their warnings as chirps and tricks to get fish.
8. The Babel Fish is a small yellow fish that is used in the novel to enable any two creatures to communicate with one another by placing one in their ear. the fish act as translators by adjusting brain wave frequencies in the speech centers of one's brain thus allowing a human being and an alien to communicate flawlessly.
9. As he continued exploring the world within The Hitchhiker's Guide to the Galaxy, Adams began to change the nature and order of certain events from the TV series, to the continued sequels, and even in the comic books. thus, there is no completely accurate version of events.
10. Douglas Adams appeared on and wrote for Monty Python's Flying Circus.
11. The Earth was created by hyper-intelligent mice in order to compute "The Answer to the Ultimate Question of Life, the Universe, and Everything" over a period of 7.5 million years.
12. Adams says that the reason he selected 42 as the answer to the Ultimate Question was because "... It was a joke. It had to be a number, an ordinary, smallish number, and I chose that one. Binary representations, base thirteen, Tibetan monks are all complete nonsense. I sat at my desk, stared into the garden and thought '42 will do' I typed it out. End of story."