Revealing mistake: The Acheron fires many devastating blows on the Surprise and the effect is visible in close-ups and a wide shot. However, after Mr. Mowett yells, "Relieving-tackles on the tiller! You men collect the wounded!" there is another wide shot of the Acheron in the foreground and Surprise in the distance. In this shot Surprise has NO damage whatsoever! (00:11:00)
Continuity mistake: When Captain Aubrey's head is bleeding after being hit during the first battle with the Acheron, we see the wound just above his eye. However, when we see him next, the wound is farther down his hairline. (00:11:50)
Continuity mistake: Jack Aubrey's hair changes in consecutive shots throughout the film. For example, when Stephen tells Jack, "Let me take a look at that brow of yours," his hair differs in the following close-up. (00:16:40)
Continuity mistake: When Jack is peering through the magnifying glass at the chart, we see 'Hidden Reef' and 'Dangerous Shoals', but in the previous shot those two things are shown way to the left of where he is looking. (00:18:05)
Audio problem: After the Acheron attack on the Surprise, below deck Jack, Stephen and some others discuss the situation. When Mr. Allen says, "Triple-shotted at 200 yards, and our guns had no effect," his mouth is actually saying, "...at 500 yards..." (00:18:20)
Continuity mistake: After Stephen asks, "What is the weather gauge?" the table in front of Jack is visible in the following shots. As Jack extols the virtues of the Surprise the position of the nautical dividers in the instrument box differ once Jack is done. When Jack points to the shoals in the close-up, the map's position under another pair of nautical dividers, the log, ink well stand, etc., is different than the previous shots of the table. (00:18:30 - 00:19:55)
Revealing mistake: The characteristics of the scarring on Jack's left earlobe changes in quite a few shots. The scar, in the shape of the letter Y, over Jack's right eye changes its angles and as for the scar at his hairline, the upper and lower line switch off being longer in length throughout the film. (00:18:35 - 00:33:00)
Continuity mistake: While Stephen performs Blakeney's amputation, the string on the hinge of Stephen's eyeglasses changes in consecutive shots. (00:21:45)
Continuity mistake: During Blakeney's amputation, the cloth roll in his mouth changes position in consecutive shots. (00:22:15)
Audio problem: While doing repairs on Surprise, Jack says, "Repair won't do here. I need those replaced," but his lips don't move when his voice says, "..replaced." Then as he says, "Ask Mr. Lamb what he has in stock," his mouth actually says something else. (00:22:55)
Continuity mistake: While performing brain surgery on Joe Plaice, Stephen, whose sleeves are rolled up to his elbows, reaches for a spoon with his freckled hand. In the following close-up it is blatantly apparent that it is not Paul Bettany's hand lifting the spoon, not to mention the bit of sleeve (not rolled up) that is visible at the bottom of the screen at the wrist. Then in the overhead shot the table with the instruments is visible, which includes the two boxes and silver spoon. In the next close-up the dark brown box's position and the spoon's position differ (before he picks up the spoon). (00:23:50)
Revealing mistake: After a close-up of the drawing of one-armed Lord Nelson, Killick opens the lid of the steaming food for Jack in a close-up, just before Killick says, "Oh, here we go again. Scrape, scrape, screech, screech." Later, after Pullings takes command of Acheron, Jack tunes up his violin and Killick says, "Here we go again," in another close-up of the steaming food for Jack. Every detail of the food shown in both close-ups is exactly the same - obviously shot at the same time. (00:26:25 - 02:05:20)
Continuity mistake: When Jack and Stephen play their musical instruments, the cloth under Jack's chin changes position in the close-up. (00:26:55)
Continuity mistake: While Jack and the rest speak about Lord Nelson, the plate of bread on the table is visible when the wide shots face Stephen. The following two close-ups show the plate of bread on the table, as Stephen looks at the weevils and the bread is positioned very differently in these shots. As Jack slams his hand down on the table, the bread is positioned as in the previous wide shots. (00:32:45 - 00:34:25)
Continuity mistake: When Stephen is pressed to examine the two weevils, in the close-ups facing Jack, even after he slams his hand down on the table, the spoon in the gravy boat leans to the side, yet, in the shots facing Stephen the spoon is at the handle. (00:34:50)
Audio problem: Jack tells Pullings that he will take the next watch. Pullings says, "Aye, sir. Mr. Mowett, Mr. Allen, calmly now. You know his orders," however he does not say the latter half of that sentence, he says something else. (00:42:55)
Continuity mistake: When Lofty asks if the Acheron is like a pirate ship, in the wide shot Davies, who holds a pipe, grabs him up. In the next close-up, the pipe Davies holds is positioned completely differently in his hand. (00:43:35)
Factual error: When the ships go around Cape Horn you see it in the distance. But the rock you see is not Cape Horn. Cape Horn is a 400 metre high rock face. (00:47:25)
Continuity mistake: When Stephen comes on deck during the rounding of Cape Horn, Jack yells to him from the quarterdeck. Jack has his boat cloak on. He does not put on his boat cloak for several shots later, just after he tells Bonden to steer SSW. (00:48:30)
Continuity mistake: After Will's death, Joe looks through Will's belongings. As the shot faces Joe he unrolls the parchment and in the next close-up of the parchment, not only do the edges of it differ from the previous and following shots, the way he holds it differs as well. (00:53:55)
Chosen answer: The flag is a signal flag, and is probably meant to signal that the ship is a whaler or engaged in fishing operations. Such flags were part of an international code, which, with some modification, is still in use today. (The flag is similar to the modern-day "Foxtrot".)