Continuity mistake: After the melee with the destroyer above the surface, they attempt to dive and travel under the keel of the destroyer to escape the deck guns. As the camera is going underwater, the destroyer can be seen, but when the camera is below the surface, its keel cannot be seen.Phil Watts
Continuity mistake: As the submarine is preparing to leave the dock in one of the movie's first scenes, Bill Paxton, the commander is standing on the top part of the sub. A seaman is walking in Bill Paxton's direction and the camera is at a distance. As the camera zooms in the man walking should have been in the frame under Mr. Paxton but he just disappeared. (00:20:20)
Continuity mistake: When the German destroyer is with U-571, look at the ship. Notice in the first shots there are 2 gun turrets on either side. Yet in the later shots during the final battle there's only one turret. In addition, right before the turrets are shown turning to fire, look at the ship again - they are already aimed at the U-boat. I guess the Germans felt the need to do this two times.
Revealing mistake: At the end of the movie, when the aft torpedo blows up the ship, the pieces that fly into the air hit the water and there is no splash. Obviously computer generated.
Continuity mistake: When Tyler is unhandcuffing Tank and Mazzola's body is lying beside him, in the long shot of the scene, it looks like Tank and Mazzola are a few feet away from each other. But in the overhead shot, they're right beside each other. (01:09:20)
Audio problem: When they spot the long range plane circling the U boat Mazzola starts yelling saying, "Do something Rabbit." A quick shot later you notice that he is still talking but his mouth is not moving. (01:06:00)
Other mistake: There is a scene where Eddie, the mess steward, is taunting the German prisoners while writing numbers on their chests. Watch his writing hand as he's working on 11. He makes an awful lot of strokes, including several horizontal ones. You can see from the next guy, 12, that Eddie's ones are just simple vertical lines, so there's no reason for him to have spent so much time writing on 11's chest. Except that it gave him time to say his whole line. (00:45:40)
Character mistake: Near the beginning of the film, when Tyler calls the crew of the S-33 to quarters, look at the guy two back from Mazzola, on the far right. He has his hands clasped behind his back while he's supposed to be at attention. When Tyler says "At ease," he realizes his mistake, drops his hands to his sides where they're supposed to be, then clasps them behind his back again as he stands at ease.
Factual error: Shortly after the crew of the S33 are forced to take to the U571 and destroy the German Supply Submarine Tyler announces that they will try to sail to Greenland or Land's End (England). From their mid-Atlantic position they would, therefore, need to sail east. In the next scene the submarine is seen on the surface sailing from left to right across the screen with the sun on the other side of them. Since from the North Atlantic the sun would always be to the south this must mean they are sailing west, away from Greenland and England and towards the United States. (00:57:05 - 00:59:25)
Continuity mistake: In both scenes when the sub is being depth charged, how come the lights keep coming on even though you see them blowing out?
Audio problem: When the U-boat captain is called onto deck,he orders his machine gunner to fire at the sailors who are rowing towards them. As soon as he fires the ammo belt gets used up straight away, however the sound of the gun carries on for a short while longer. (00:27:50)
Character mistake: After accurately depth charging U-571, the German destroyer crew suddenly turns out to be almost comically and unrealistically incompetent at the end of the movie. Not only do they barely hit U-571 with their guns, but they also can't keep up with the sub. But even with both submarine diesel engines running flank speed (of which U-571 only has one badly damaged engine operational), a common WWII destroyer would easily be twice as fast as a Type VII U-boat. The destroyer could swiftly close the distance and could either ram U-571 or cross the sub's wake to bring all its weapons to bear and make it more difficult to get hit by the sub. Of course the destroyer doesn't do that but stays perfectly in U-571's wake for an easy kill shot from its stern tube. In reality, it was considered an incredible feat to sink a destroyer with a torpedo, since they were agile at full speed, could easily dodge torpedoes and had shallow draft. This destroyer crew however, seems actively trying to get killed.