This year is a pretty special year for The Hitchhiker's Guide To The Galaxy, as it has been 42 years since the original BBC radio series was first aired. Douglas Adams later expanded his off-beat space-opera into a series of novels which further cemented his work as one of, if not the most, successful and popular comedic science-fiction series of all time.

RELATED: 7 Sci-Fi Books Better Than The Movies (& 8 That Are Surprisingly Worse)

It soon after developed into a television show and video game but it was only in 2005 that a movie was released. As with each reiteration of The Hitchhiker's Guide To The Galaxy, there are always some notable differences.

Ford And The Bulldozer Scene

The Hitchhiker's Guide To The Galaxy is known for its off-beat and sardonic humor and one moment that exemplifies this is Ford convincing the councilman to take Arthur's place in front of the bulldozer that is meant to be demolishing his house.

Ford reasons that since Arthur Dent (Martin Freeman) was going to stay in front of the bulldozer the whole time anyway, his place can easily be taken up by someone else in order to allow for things like going to the pub. Unfortunately, this hilarious and ridiculously odd moment is missing from the movie and Ford (Mos Def) instead gives the demolition crew a few beers to stop them from working.

Vitvodle VI And Planet Vogsphere

For a book that is set in space, the crew of the Heart of Gold does very little space travel and only visit one planet, Magrathea.

Yet, in the movie, the group not only goes to Vitvodle VI, the small planet of the Jatravartid people, but they also travel to the dreary homeworld of the Vogons, Vogsphere.

The Towels Are A Lot More Functional

As all fans of the series know, the most important thing a hitchhiker has is a towel. In the book, this appears as a quaint entry in the guide and it explains the practical and more importantly, the psychological value of having a towel. Yet, throughout the book, Ford and Arthur don't really make use of their towels.

The movie completely skips the towel entry but throughout, Ford and Arthur are rarely seen without their trusty towels. They use them as scarfs, shields, and even as a weapon to catch a spatula-shaped creature that slaps anyone with an idea on Planet Vogsphere.

Humma Kavula And Questular Rontok

Humma Kavula (John Malkovich) and Vice-president of the Galaxy Questular Rontok (Anna Chancellor) are two characters that only exist in the film. Kavula is a former political opponent of Zaphod's (Sam Rockwell) and a leader of the Jatravartid religion. They believe that the Universe was sneezed out from the nose of a being called the Great Green Arkleseizure. Rontok acts as Zaphod's second in command and is also madly in love with him.

While Kavula is completely new to the series, the Jatravartids appear in the second book in the series The Restaurant at the End of the Universe. Although Adams died before the movie was released, he still had substantial input on the film and he specifically created Kavula for the movie.

The Vogons

One of the most noticeable changes in the film was the continuous presence of the Vogons, a truly unpleasant species with an absurd devotion to bureaucratic order. In the book, they are Arthur's first introduction to a truly alien species and serve as a way for Ford and Arthur to get on to the Heart of Gold.

RELATED: The Wizard Of Oz: 5 Things The Movie Changed From The Book (& 5 That Stayed The Same)

They become the main antagonists of the movie. Along with Rontok, they are tasked with retrieving the stolen Heart of Gold. They even take Trillian (Zooey Deschanel) to Vogsphere and nearly kill the Paranoid Android, Marvin.

What Happens On Magrathea

Magrathea is a planet home to a luxury planet building service and on it, Arthur discovers that Earth is actually a complicated computer program meant to figure out the ultimate question of life, the universe, and everything.

In the film, Ford, Zaphod, and Trillian go through a portal, where they get to meet Deep Thought and are given the Point Of View Gun, while in the book, they are held captive in a catalog room. Notably, the movie version sees Arthur going to the new Earth to have a meeting with the mice in an exact copy of his house, while in the book, it all takes place in a waiting room belonging to the Magratheans.

Point Of View Gun

The Point of View Gun was also another one of Adams' original ideas. A rather ingenious weapon, it allows the user to transfer their point of view onto their victim. It was designed by Deep Thought after it was commissioned by the Intergalactic Consortium of Angry Housewives to get their husbands to understand them better.

RELATED: 10 Best TV Adaptions Of Sci-Fi Books

While on Vitvodle VI, Humma Kavula forces Zaphod into retrieving the gun from Magrathea by holding his other head hostage. Kavula wants to use it in order to convert more people to his religion.

Arthur And Trillian's Relationship Is More Intense

Arthur and Trillian talking in The Hitchhiker's Guide to the Galaxy

No movie is complete without a love story and the film version of The Hitchhiker's Guide To The Galaxy certainly held nothing back. In the book, Arthur and Trillian's relationship cools off slightly and it doesn't feature strongly in the overarching story.

However, their relationship is far more intense in the movie and Arthur is completely and sometimes embarrassingly infatuated with Trillian. She eventually realizes that she feels the same way. Adams was also behind this significant progression of their relationship for their story to be better suited for film.

Everything About Zaphod Beeblebrox

Out of all the characters in the book, Zaphod Beeblebrox is perhaps the most different and his portrayal in the film is often the most criticized by fans. The film version of Zaphod is a lot more obnoxious and idiotic and overall lacks the depth and complexity of the book character.

More importantly, the film completely skipped over the important and intriguing revelation that he only became President of the Galaxy to steal the Heart of Gold and that he had taken out parts of his brain to hide from the scans that he needed to take in order to become president.

Earth Gets Replaced

Most movies have a happy ending and The Hitchhiker's Guide To The Galaxy is no exception as the destroyed Earth gets replaced. After Arthur had squashed the mice and Marvin had defeated the Vogons with the Point of View Gun and his depressive thoughts, Earth carries on as if nothing happened.

Yet, this doesn't happen in the books, and Earth is lost forever. That is until the fourth book, So Long and Thanks for All The Fish, where the Earth mysteriously returns.

NEXT: 10 Classic Pieces Of Literature With The Most Cinematic Adaptions