The sonar ping sound effect is wrong. Throughout the movie you hear ping-and-return (echo) 2-tone sound effect, the return echo coming closer and closer as the ship passes overhead. This is the sound the sonar man on the ship (not the submarine) would hear: his sonar's ping and the echo off the sub. In the sub, you would hear the ship's ping and that's all. If you hear ping-and-return in a sub, then you are listening to the sound of the submarine's own active sonar.
In one scene several American sailors are wearing German uniforms with the swastika insignia on opposite sides of their shirts. In another scene, American sailors in dress uniforms are wearing ribbon bars for awards that did not exist in 1942.
In the scene before boarding the submarine, a box of explosives is shown but the sign on the box is an international United Nations symbol for explosives (exploding device on orange background). The UN was not created until after WW2
Hirsch mentions that the location is "near the CHOP line", which is boldly marked on the map at 30°W. The CHOP line, indicating where a convoy's protection CHanged OPerational control from American or Canadian to British responsibility, was first established on July 1, 1942, but the letter that, in his first scene, Tyler has just received is dated May 14, 1942. Also, the CHOP line was initially at 26°W and then 47°W, never 30°.
While boarding the U-Boat, Lt. Tyler slowly walks the length of the boat with his hand gun extended using the Weaver Stance. The Weaver Stance, a two handed grip, was developed during the late 1950s by Deputy Sheriff Jack Weaver in California. Before that time, especially during the war, the single handed side grip was taught and used.
The captain congratulates his gunnery officer for destroying the radio tower of the German ship, saying the tower "is history". The expression "(something/someone) is history", meaning it/he/she is dead or destroyed did not come into popular usage until the 1980s.
In the scene with the life boat, the machine gun used is clearly a MG-42 or some variant, however, when the machine gun is fired the sound we hear is more similar to a .50 caliber Browning, a gun used by the US army, not a Nazi u-boat.
The machine gun that the Germans are using to massacre the British sailors in the lifeboat is an MG-34, which had a rate of fire of roughly 900 rounds per minute. The audio is of a machine gun firing much slower, at around 500 rpm.
Hirsch says that the sub was attacked and presumably disabled "last night at 0300 hours". This is impossible for several reasons; for one thing, the S-33 could not have been sent out when it was. He must mean the previous night.
In the scene in which the men are in bunks and Mazzola is talking about a girl he met, he says when he's not "getting anywhere" with her, he uses his secret weapon: the story of the S-26. He then says, "She was running a test dive down off Norfolk. Shaft seal failed. She sunk to 400 feet." This is incorrect. The S-26 was accidentally struck by PC-460 (USS Sturdy) and sank during night patrol maneuvers in the Gulf of Panama in January of 1942.
When Lt. Tyler is sitting on the porch smoking a cigar the first shot shows it half finished, then the next wide shot shows the cigar full, then the next shot is another close up with the cigar half finished again.
When Hirsch is briefing the crew of the S33 he is pointing things out on a chart. When you first see the chart table the only thing on it is a brown folder. In the close up you see the folder and a photograph of the Enigma machine. In the next shot you see the complete table again but only the folder is on it again. Hirsch then pulls the photos out of the folder.
At the start of the film, just after the fire starts in the German sub's diesel room, an officer shouts, "She's dropped to 120 meters, Captain." Close examination of the depth gauge to his right shows the sub to be rapidly surfacing.
When the Captain is summoned to the outside of the U-571 by the crew (U.S.), he confronts a German destroyer dead ahead, blocking their path. We clearly see the guns aiming directly at the U-571 at this point (only for a moment, as the Captain emerges from the sub). Yet moments later, when the Captain orders his crew to fire on the destroyer's radio, the destroyer responds by turning its guns towards the U-571, because they are now shown pointing in another direction.
When the German sub comes across the lifeboat full of survivors, the gunner is shown with a long strand of cartridges that loops down to about his knees. When he begins firing, the strand pulled from his outstretched hand is no more than two feet long, yet the shots ring out for some 15 seconds.
After the U-571 deck gun fires at the destroyer, wrecking the radio room and mast, the crew hurry back to the conning towers as the U-Boat dives. In doing so, they fail to replace the watertight cover on the barrel of the gun (shown in close-up as the crew scramble for the tower), yet moments later, as the U-Boat passes under the destroyer after submerging, the cover can clearly be seen on the end of the barrel.
After the team takes the enemy U-Boat and they have to use it to escape the German resupply U-boat, Lt. Tyler is rapidly turning two dive valves in one direction. In the next scene, he is rapidly turning them in the opposite direction.
While Lt. Tyler is looking through the binoculars at the German destroyer the guy behind him is also looking through binoculars. Then there is a medium shot that shows him not looking through the binoculars. Then there is a close up again of both of them looking through binoculars.
Tyler's body position changes between when he punches Mazzola and when he says "What are you doing? This is not a God damn democracy." He is facing a different way and is grabbing Mazzola with his left arm.
After diving to avoid the German Submarine, The chief requests to shut down the main vents. He and Mr. Tyler rotate wheels on opposite sides of the control room. In the first shot Mr. Tyler turns he wheels counter clockwise, but in the next shot he is turning them clockwise.
When U571 first meets the German destroyer there are two ships used to play the Z49. In most shots the ship has five turrets but as the small launch comes up next to U571 and the Lt says the line "Tell them to go away" in the next shot of the ship you can see it only has two.
After the U571 blows up the German destroyer radio tower the resulting smoke and fire comes and goes between shots. Sometimes there is thick black smoke then in the next shot it almost goes out with just faint gray wisps and then goes back into full black smoke after.
The S-33 starts from Kittery, Maine ("PORTSMOUTH NAVAL SHIPYARD" on building behind welders), but in Lt. Hirsch's briefing, the map clearly shows the U-571's triangulated position at 52°N, 29°W. This is over 2,000 miles from Portsmouth, NH, but only about 1,200 miles from Lorient, France. The resupply sub left Lorient before the S-33 left Portsmouth (known from the times of day and also because Hirsch knows about it), and the U-571 is drifting east, too, so how could the S-33 possibly get there first?
A comment was made that Chief Klough was to have said he was depth charged off "Murmansk" (and even the closed-captioning said that) but the proper reference is "Merignac" a French city then at the end of an estuary but now close to Bordeaux, France.
After Tyler decides to head for Lands End (England) the next morning shows an exterior surface shot of U-571 running on the surface at dawn. The sun was rising a few degrees forward of their port beam, indicating that U-571 was heading south, not NNE as they would if heading to Land's End from their Mid-Atlantic position.
The German recon aircraft appears to be a Messerschmidt 109. However, the head on view is that of another aircraft (wrong wings). The big question is: What is a German fighter doing in the middle of the Atlantic? There were no German aircraft carriers. Recon aircraft were float planes, launched from catapults.
The crew is shown taking in lines when the boat is preparing to get underway. Lines were not stored aboard the submarines in the line lockers provided because under depth charging, the lockers could open and the lines could get loose and foul the screws or dive planes. Submarines cast off the mooring lines to the tender.
The area around the coast of the UK was patrolled by aircraft of RAF Coastal Command and as the U-Boat is heading for the UK (on the grounds that it is too far to return to the US with such a damaged boat), the PBY Catalina that is seen in the last shot, should be wearing RAF roundels not US-Navy (pre-war/neutral) markings.
When Lt Tyler is reading the document in his car, the date at the top of it is "May 14, 1942". Military dates on documents are always in a day - month - year format, so the date on the document should have been "14 May 1942".
The CPO said that he had been depth-charged in WWl in a US sub by a German destroyer near Murmansk. This would have never happened. First, US subs did not operate there or at all in Europe then. The closest allied subs would have been British ones hunting German ships in the Baltic. Why would a US sub in WW l or ll be any where near Murmansk , which wasn't even a port then, it was Archangel? Any ships heading that way would be allied vessels with supplies for the Russians, and subs had only one use, to sink enemy merchant vessels. And what would a German destroyer be doing there, hunting subs that couldn't attack any German ships. The German fleet almost never left the Baltic or North Sea and when they did, it would be a major task force. A lone destroyer operating 1000s of miles from port in frigid enemy waters to hunt subs that wouldn't be there in the first place makes no sense.
The "destroyer" is identified as the Z-49. The Z-49 was planned but never built by the German Navy. Had it been built, it would not have been completed until very late in the war, long after the time of the movie. Further, the ship shown in no way resembles a 1936C type of German destroyer.
In reality, the submarine U-571 was never actually captured. The submarines U-559 and U-110 were the ones captured with the codebooks but by the British Navy in August 1941, four months before the United States entered the war.
In the engagement with the other U-Boat, U-571 fires four torpedoes in quick succession without taking on trim water, yet the U-Boat does not change depth or trim. Each torpedo weighted from 1.5 to 2 tons. The sudden removal of that weight would cause a submarine's bow to move upwards if not countered. This is one reason why normal practice was to space the firing of torpedoes by 8 to 10 seconds, which allowed the submarine to take on water to compensate for the lost weight.
When the American submarine first dives, the chief of the boat Harvey Keitel incorrectly sounds the dive alarm 3 times and says "dive, dive, dive." The correct procedure for diving is two 2 times on the dive alarm with the announcement of "dive, dive," and surfacing is 3 times on the dive alarm followed by "surface, surface, surface."
The Captain explains the reason Tyler wasn't promoted was because he is too close to the crew and wouldn't be able to give them an order that would result in their deaths. The navy always assigned promoted XO's to new boats anyway precisely because of this problem.
Key members of the crew are sent as the boarding party - the sonar man, the chief of the boat, the XO, the radio man. In reality the S33 captain would not have risked his key crew for a boarding party.
The German destroyer is shown blown to little bits in a huge ball of flame from one torpedo. This would not have happened, especially in the bow shot depicted. One torpedo might create a 30 foot hole in the bow, and possibly the ship would have sunk, and possibly it might have stayed afloat, as many navy ships with sealable compartments did.
When the Germans are attacking the freighter in the opening scene, the torpedo has a run time of roughly 12 seconds for a target 500 meters away. At 35 knots, it would take a little under 30 seconds in order to reach a target at that distance.
Several times the American crew of U-571 mention that the starboard engine is out and they can only run the port screw. But every time you see an underwater shot both of the screws are turning equally.
As shown in the movie, the code book which cracked Enigma during the Battle of the Atlantic was the long weather code book. This was only captured once - by the British. Subsequent attempts by the US failed as the book would dissolve on contact with water. The film does not purport to be telling a true story; a notice at the end acknowledges the real-life ships whose crews captured Enigmas.
It was the British who managed to get hold of the machine in May 1941, not the US Navy crew capturing it by boarding a U-boat. While the US Navy probably would not have boarded a U-boat before they joined WWII, the title card at the beginning explicitly states that the film takes place in May 1942, six months after the US became involved. Furthermore, the film acknowledges the successful British attempt a year earlier and, once again, is depicting a fictional operation, not a factual one.
A black character has a prominent place in the movie, from the crew of the U.S. sub. While sub crews were not fully integrated at the time, African-Americans did serve, as shown here, as messmen and stewards.
While testing the German of the soldier, the officer refers to the German town of "Koblenz" at the river Rhine. The name of that town is written "Koblentz" in the English subtitles, but this is a common alternate spelling and helps emphasize the pronunciation issues.
It is claimed that the U-571 is meeting a supply U-boat. It supposedly is this supply submarine which sinks the S-33. At the time of the movie the German supply submarine was the Type XIV, commonly known in English as the "Milk Cow". Such a submarine could not possibly sink the S-33, since the Type XIV was not equipped with torpedo tubes.
S33 is supposedly made to look like a German sub but another German sub sinks them. At night, in a storm the other sub would not be able to identify them, but if it was sent on a mission to rescue a sub, why would it shoot first and ask questions later? Wouldn't they have tried to identify it as definitely not the ship they were supposed to rescue with their Aldis lamp as the S-33 had done minutes before with U-571?
At the beginning of the movie when the U-571 is under depth charge attack from the British destroyer, the order is given to surface the sub due to damage. When they surface, the Captain reports "All clear!" and orders lookouts to the bridge. What happened to the British destroyer that was just attacking them? It should have still been nearby and would have seen them surface.
When the U-571 sends its distress message, the toothed wheels of the Enigma machine are visible while three characters of text are typed. The right-hand wheel should advance with every character, but it clearly does not; in a close-up we see it advance correctly once, then on the next character it just starts to move and falls back. Presumably the filmmakers used a real wartime Enigma machine that, after 55 years, was not in good working order.
There is a scene where the guy is in the sonar room. Then there is a shot that shows the length of the corridor. If you look down at the end of the corridor there is a guy that walks into the corridor from the side and stops and looks down the corridor toward the camera.
When the German destroyer explodes after being struck by the torpedo, large chunks of metal are shown through the periscope to be raining down as a result of the blast. These large pieces of metal make absolutely no splashes when they hit the water. In fact, the water around the destroyer is completely calm, despite the fact that there had just been a series of large explosions.