Other mistake: If the scene in which Jack Aubrey gives the order "hard a larboard" [meaning the opposite of starboard] was indeed a rudder order (ie. turn the rudder in the direction commanded, which turns the ship the other way, in this case to starboard) the face of the compass wouldn't have rotated clockwise. The compass shows a southerly course, rotates clockwise, and eases to show an easterly course, which is a 90 degree turn to port.
Trivia: When Captain Aubrey makes the toast 'To wives and sweethearts - may they never meet' he is following a custom in the Royal Navy called the toast of the day. There was a special toast for every day of the week. This one in particular was usually for Saturdays. There is a minor mistake, however: tradition dictated that the proposer (in this case, the captain) would say the first part 'to wives and sweethearts', to which the most junior officer present would reply 'may they never meet'. Here is the list that seems to be most commonly followed dates from before Trafalgar, courtesy of the Canadian Navy website: Monday - our ships at sea, Tuesday - our men, Wednesday - ourselves, because no one else is likely to both, Thursday - a bloody war or a sickly season (to ensure quicker promotion), Friday - a willing foe and sea room (The two preceding seem to be of historical interest only), Saturday - wives and sweethearts - may they never meet (reply is made by the youngest officer present) Sunday - absent friends.