Factual error: When Roberts makes a deal with the Captain, he demands that the Captain grant liberty to both sections (i.e., the entire crew), leaving only Roberts and one enlisted man aboard as the deck watch. All U.S. Navy ships must have enough personnel aboard at all times to get the ship underway immediately, if necessary, which is why the crew is divided into watch sections.
Continuity mistake: In the scene where the Reluctant is in the port of Elysium and the men are on shore leave, a truck load of MPs show up. Ttheir patrol leader tells Mr. Roberts that his men will be stationed along the starboard side of Mr. Roberts ship for the remainder of its stay in port because of the problems various members of the ship had been causing while on shore leave. No sooner do the MPs line up along the side of the ship do you see one of the ships crew flying down the dock on a motorcycle. When the motorcycle passes the ship the MPs who just 10 seconds before were lined up along the ships starboard side are now nowhere to be seen.
Factual error: The Captain, Roberts, Pulver, and the doctor are the only officers ever seen or mentioned. No Executive Officer, and no officers in Deck, Engineering, Operations, Supply, etc. Also, Dowdy is apparently the only Chief Petty Officer on board.
Suggested correction: Other officers are on board. When they are loading supplies to one of the landing craft, an officer tells Mr Roberts to keep any fresh fruit on board for the Captain's mess. That man is dressed in Khaki's and is not Pulver or the Dr. Also, we never see the entire crew, at most we see 20-30 men. Other CPO's can be on board, just never seen.
Factual error: Pulver supposedly had been on the ship for 14 months without the captain knowing he was aboard. But, the captain would have had to interview him when he came aboard, assign him his duties, and complete a fitness report on him every six months. In addition, all of the officers take their meals in the wardroom, so the captain would have seen him several times a day.
Factual error: There is no such thing as a Laundry and Morale Officer. The ship's laundry was under the auspices of the Supply Officer, as were numerous other functions. In the novel on which the movie was based, Ensign Pulver was described as "one of the engineering officers."
Continuity mistake: When Frank gets his mail, he first reads out loud the letter from Doug, but then the next letter says that Mister Roberts, Doug, is dead. Depending on the cameras' viewpoint, the letter is crumpled, then not, then crumpled again before Doc takes it away from him.
Continuity mistake: In the opening scenes, Mister Roberts is sitting on the deck of the ship with a folded piece of paper in his hands, but when Doc approaches, the paper is now unfolded.
Factual error: The captain walks through the wheelhouse to the outer deck to water his potted palm tree. Even though the ship is at sea, there is no one on the bridge, and the ship's wheel can be seen through the window, moving back-and-forth, steering the ship by itself. A naval ship, particularly during WWII, would always have a crew at the helm and the wheelhouse would never be left empty.
