Trivia

The producers have stated that this movie was not a literal translation of the books (just as the books were not a literal translation of the original radio show), but all of the new ideas and characters came from Douglas Adams. The hired writer simply came aboard to improve structure and make the screenplay more coherent.

Deep Thought explains the significance of the number '42' at 42 minutes into the movie.

According to the DVD commentary, the animators who created the animated Guide entries would occasionally sneak in hidden in-jokes into their animations that were deemed too inappropriate for a family movie and had to be removed. One of these jokes which wasn't removed is an animation explaining the Babel fish and how a farmer becomes repulsed when he learns that a cow is somewhat aroused by being milked.

Easter Egg: The DVD includes an "Improbability Drive" item on every menu. Clicking this leads to a random point in one of the bonus features. Used several times leads to a strange cartoon, which is the same one Deep Thought watches.

This movie was in "development hell" for over 15 years. At one point, Douglas Adams insisted it would be made "sometime before the last trump". Just prior to his death, a deal was almost in place with Jay Roach directing and starring Hugh Laurie (Arthur), Jim Carrey (Zaphod Beeblebrox), and the late Sir Nigel Hawthorne (Slartibartfast).

Su Elliot: When Ford Prefect and Arthur Dent drink at the pub early on, a middle-aged blonde woman can be seen watching them. According to the DVD commentary, she played Trillian in the London stage version of the story, a fact of which director Garth Jennings was unaware until the day of shooting.

Simon Jones: The original Arthur, handpicked by friend Douglas Adams for the radio show and television's The Hitch Hiker's Guide to the Galaxy (1981), makes a brief appearance as the Magrathean "greeting/threat" holomessage. This marks another slight deviation from the other Guide incarnations, as all of the other versions used Slartibartfast's likeness for the holomessage.