Continuity mistake: When Vincent Kapoor is talking about getting Congress to fund a sixth Aeries mission, he states Aeries 3 evacuated after 18 SOLs. Near the beginning of the movie, after Mark Watney regains consciousness and returns to the HAB, you see Rover 2 parked behind the HAB with the crew cab facing away from the HAB. Later when Mindy Parks is comparing the SOL 18 and SOL 54 pictures, Rover 2, in the SOL 18 picture, is turned 180° (with the crew cab facing toward the HAB) from what we saw when Mark returned to the HAB on SOL 18.
Continuity mistake: When Bruce Ng is video calling Teddy Sanderson and Mitch Henderson to explain the modifications Watney will need to make to the Ares 4 MAV, there is a point in which the model MAV behind Bruce contains only a chair, all other chairs and the control console having been removed. Then, as Bruce and Mitch explain to Vincent that since Martinez will be remote-piloting the MAV, Watney doesn't need the controls, there is a shot of Bruce pulling several chairs and the control console out of the model.
Continuity mistake: In the shot where Matt Damon finally gets captured by his rescuer, he is face to face with the woman astronaut and when he smiles his upper teeth are Hollywood white. In earlier shots, his teeth were shown stained and nasty. Also, shots soon after the rescue "white upper teeth" shot again reveal stained teeth.
Continuity mistake: When Watney is putting duct tape on the plastic patch over the hole where the Hab airlock blew out, the first shot shows him outside the Hab putting the last strip in an evenly distributed set, from about the 10 o'clock position down to about the 4 o'clock position. Then (after a quick reverse shot from the interior), suddenly he is placing a new strip up from the 8 to 2 position, covering a spot that was already covered when he did the 10 to 4 strip, but which is now suddenly blank.
Continuity mistake: This mistake is in the extended edition: When Watney decides "I'm not going to die here", he packs up his five crew mates' belongings in plastic boxes and stows them in one of the two bottom bunk beds, from which the mattress has been removed. Then Watney is shown struggling out of bed, presumably the next morning, and a wide shot shows all six bunks. Every bed has a mattress and bedding on it and there are no boxes in sight. (00:19:10 - 00:19:50)
Continuity mistake: After breaking his helmet (with the "2" on the right side camera and with the name "Watney" on the back, he replaces it with one with no name and no number on the camera. However during the scene when he is preparing for the final trip, in shots of him manhandling solar arrays he has his old helmet on again. (01:34:25)
Continuity mistake: During the segment showing the rocket carrying supplies exploding, Teddy is shown in the background walking out of the control room. However in the next scene Teddy is standing with others in the control room.
Continuity mistake: When Watney decides to retrieve Pathfinder, the date is sol 79. On earth Vincent says Watney has been traveling in the same direction for 13 days, and maps Watney's position as about one quarter of the way to his target. However Watney's helmet readout shows him arriving on Sol 94, only 14 days after he probably left the hab on sol 80. (00:42:00 - 00:44:00)
Continuity mistake: When Vincent draws the line on the Martian landscape picture and comes to the conclusion Mark is heading for Pathfinder, in the long shot, Mindy, who is standing next to Vincent, holds her left hand up by her face and her right arm down by her side. As Vincent begins to walk away, the camera instantly cuts to a close up of Mindy's face and now her right hand is up by her face and her left arm is down by her side.