Continuity mistake: When Kenny is brought into the hospital, there is a schedule on the wall next to the door (Dr. No is scheduled to 'Kill Bond'). When Kyle is worried that their Mums will find out that they went to the movie, the Doctor column has vanished from the chart. A little later, the columns are reversed.
Continuity mistake: After Gerry gets smacked in the face by the 'broken' suspender clasp, we see the silver clasp land under the dresser. Yet, when he's moaning and lifting his leg to get onto the bed, we can actually see the clasp still intact on the front suspender that came loose, which is dangling right behind him (just look between his legs). Of course, in the next shot, that clasp is gone. Since the silver clasp is one of the plot points, this is bizarre to say the least.
Continuity mistake: When John and Catherine are in the hangar at the runway, the Cessna's tail number is N3035C. When the plane is shown in the air, the number is N3973F. When they land, the tail number has changed back to N3035C.
Continuity mistake: In the bedroom scene the girl is holding a clear cup full of beer. The camera goes off her and when it comes back she is holding a blue cup. The camera goes back off her then on her and the cup is clear again.
Continuity mistake: When Sam is in his bedroom, after he finds the Cube sliver it falls and dramatically burns a hole through the floor into the kitchen. But Sam's bedroom is over the living room (there is nothing on the ground floor below Sam's elevated bathroom, and in the first movie Jazz hides in this open space), and the kitchen is actually located between the den and dining room, at the other end of the house. If they were to follow the actual floor plan of the house, the Cube sliver would have landed in the area of the piano in the living room, but where would the fun have been in that?
Other mistake: When devising the plan to retrieve Watney, it is mentioned that the Hermes crew have had to lash together all the webbing on board to make the longest possible tether. When this tether is used, there is no evidence of any lashing together or other extensions or modifications to lengthen it. The tether is one continuous length and is stored on a reel that was designed for the length of tether gathered on it.
Factual error: When the exchange is made in Berlin it is bitter winter with snow on the ground. But Donovan returns to New York (the TV newsmen is reporting that Powers has been returned "earlier this morning") so it is within hours, and yet the leaves on the trees in NY are green, the grass is green, people are in shirtsleeves. Berlin and NY share the same seasons.