Adams (the Hitchhiker's Guide to the Galaxy series, etc.) contributed the idea, such as it is, while Monty Python's Jones wrote the book.
Planet Blerontin's greatest architect, Leovinus, has designed and built Starship Titanic, the biggest, most sumptuous, most advanced spaceship ever. On the eve of the ship's launch, he finds that, what with huge cost overruns, the ship isn't even half complete and its robot brain, Titania, has been unplugged; worse, the manager, Brobostigon, and the accountant, Scraliontis, are plotting to scuttle the ship and collect the insurance money. Off thunders the ship with only Leovinus and The Journalist aboard; it undergoes Spontaneous Massive Existence Failure and ends up on Earth, where it acquires three passengers- -Lucy, Nettie, and Dan, who must contend with supercilious robots, lascivious aliens, talking bombs, mad parrots, and a Captain's Bridge that consists entirely of video-game consoles.
Both Jones and Adams possess impressive comic credentials, so there are some amusing moments--but otherwise it's pretty thin and familiar fare.