The Martian: Differences between Book and Movie

First let me say that the movie is very true to the book.  I saw the movie, read the book, then saw the movie again.  The first time I saw the movie, Mark said something that didn't make sense to me.  He said "If the Hab breaches, I'll just kind of implode" but in the book he says "explode" which is correct.  I don't know why they changed that word making it less scientifically accurate.  The pressure would suddenly drop and he'd essentially get a bad case of the bends.  Air bubbles would form in the small blood vessels of his brain and he'd essentially have a stroke and die.  With gases expanding in his body due to the low pressure, explode is more accurate while implode is just inaccurate.

In the movie, one rover is destroyed in the storm so he only has one rover but in the book he's got two rovers the whole time.

In the book, Mark is a botanist and mechanical engineer. They only mention he's a botanist in the movie.

In the book Venkat Kapoor is a Hindi Indian but in the movie he's named Vincent Kapoor and is black.

In the book, when Mark is told to watch his language because the world is watching, he types "Look! A pair of boobs! -> (.Y.)".  In the movie, we only see the reaction and Teddy must apologize to the president and says "he didn't mean it.  He's under a lot of stress."

In the book, Mark uses a spare space suit to hold water.  We don't see that in the movie.

In the book, Mark uses every surface possible for his farm in the Hab.  In the movie, he just utilizes one room.

In the book, Mark injures his back carrying rocks so he builds a hot tub to soak.  This does not happen in the movie.

In the book, he never finds the communication dish that hit him, which is why he can't communicate with NASA.  In the movie, it's right next to him in the sand and yet he never tries to repair it.

In the book, Mark listens to Johanssen's Beatles collection but in the movie, all he has is disco from Commander Lewis.

In the movie, he cuts a hole in the roof of his rover but they never make it clear why he did that.  In the book he does it to make room for some equipment he requires on the trip.  In the movie, NASA and Mark both jump on the drilled out section and fall into the rover cabin.  He doesn't do that in the book.  Instead NASA has him file out the plastic between the holes.

When airlock 1 breaches in the book, the glass on his helmet shatters.  In the movie, it only cracks with a small hole which he tapes up with duct tape.  The book also goes into detail why and how the airlock fails.  The movie provides no explanation.

Although his crop dies in the movie, in the book, we later learn that some of the bacteria survived and that he could create a new crop if he wants, but never does.

In the book, it's discussed if the rescue ship fails to get the re-supply, then all members would take a suicide pill except for the smallest member.  The dead crew members would be put into cold storage and she would feed on them if necessary.  Better to have one member return alive than none.  Mark would not be rescued either.

In the book, Mark creates a bedroom he can attach to the airlock of the rover so he has more room to stand and stretch during the long trip to the MAV.  This is never mentioned in the movie.

In the book, he accidentally shorts out Pathfinder, destroying his ability to communicate with NASA until he reaches the MAV.  His journey to the MAV is far longer than shown in the movie and he has to drive around a dust storm and accidentally rolls the rover and the rover his towing, referred as the trailer.  He's OK and has to roll them back on their wheels and keep going. None of that is in the movie.

In the movie, Mark removes all the dirt from the Hab but in the movie, he just leaves it there.

In the book, he has to use most of his water supply and start saving his urine so they can turn it into more fuel.  He removes the nose of the ship and covers it with canvas and it tears away.  In the movie, it tears away completely.  It the book, it just tears.  In the book, it's more clear that this threw off the aerodynamics and made the lift-off sluggish, which is why his orbit isn't high enough.

In the movie, Mark is approaching the MAV in his rover and talks about being the fastest man in space.  He mentions how he likes that but don't tell NASA that.  He doesn't say this in the book.

In the movie, they blow a hole in the outer airlock door on the Hermes but in the book, they open the outer airlock and blow a hole in the inner airlock door so the air exits uniformly.

In the movie, Mark pierces his glove in order to fly like Iron Man to get rescued since the tether came up short.  In the book, the tether is long enough and Mark is clipped to his rescuer and pulled to safety by the tether.  Mark does suggest the Iron Man maneuver in the book but never does it.

In the movie, Mark turns off his mic so nobody hears him scream from the pain of his broken ribs.  He then says "It's true, you know. In space, no one can hear you scream like a little girl".

In the movie, they show Mark back on Earth teaching a course at NASA, Beck and Johanssen have a baby and Rick Martinez gets to pilot another mission.  The book ends shortly after he's rescued.  He's checked out by the doctor, has two broken ribs and has some final thoughts about how it's in our nature to rescue each other, then comments on how bad he smells and says it's the happiest day of his life.  End of book.

This isn't all the differences of course.  Just the main ones I could remember.