* BreakthroughHit: For both Creator/WolfgangPetersen and [[Creator/JurgenProchnow Jürgen Prochnow]]. And - at least in German cinema - for most of the cast. They deliberately cast little known actors and virtually all of them have gone on to become HouseholdNames. Herbert Grönemeyer (playing the role of the Reporter) however would become way more famous as a singer, than for his acting.
* CompletelyDifferentTitle: The French title of the book is ''The Styx'', named after the [[Myth/ClassicalMythology Greek mythology]]'s river to TheUnderworld. The film's title in France, however, was translated as ''Le Bateau'' at first ("The Boat", literal French for "Das Boot") then later [[UntranslatedTitle reverted to its original iconic title]] for subsequent video releases and general film talk.
* DawsonCasting: Klaus Wennemann, who portrays the Chief Engineer, was forty one years old when the film was produced. The actual Chief Engineer of U-96, Hans Peter Dengel, was just over twenty five during his first patrol onboard the submarine.
* DisownedAdaptation: Lothar-Günther Buchheim (the novel's author) apparently hated the movie for being a 're-glorification' of submarine warfare and too pro-German and pro-war (unlike the ''clearly'' anti-war novel it was based on) [[ArsonMurderAndJaywalking and for the cast's constant overacting]]. This has led to a DeathOfTheAuthor reaction from many of the film's fans; when he claims that the movie "re-glorifies" the U-Boat Corps, the most common reactions are "How in the world is ''any of this'' [[WarIsHell supposed to be glorious]]?" - and "If the author considers ''this'' a glorification of WWII Era submarine warfare, how miserable must it have been in actuality?"
* EnforcedMethodActing:
** The actors were not allowed to expose themselves to sunlight a few months before shooting. Also, the scenes were more or less shot chronologically, so that their appearances would change realistically.
** Jan Fedder, who played the injured sailor, really was injured when a special effect went wrong.
** In the scene at La Rochelle harbor near the beginning, actor Otto Sander, playing a drunk Phillip Thomsen really ''was'' drunk. Originally another actor was slated to play that part, but he was fired before filming began...ironically enough, because ''he'' was too drunk all the time.
** The cast were required to run drills of the emergency dive sequence, to ensure they were able to convincingly carry out the tasks the real crews had to perform during an emergency dive.
** Also the moldy rotten bread... Was really moldy rotten bread. Yuck.
* FakeNationality: The Austrian Creator/ErwinLeder as the German Johann, though might be subverted -- Johann speaks with a Southern Bavarian/Austrian accent. Austria was part of the [[UsefulNotes/NaziGermany German Third Reich]] between 1938 (when the Anschluss happened) and 1945.
* HeyItsThatPlace: The sub pens of La Rochelle were also featured in ''Film/RaidersOfTheLostArk''.
* LoopingLines: Because the camera was very loud and the submarine set very cramped, all of the actors had to redub their lines in German.
* MultipleLanguagesSameVoiceActor: Nearly the entire cast redubbed themselves into English. The only exception was Martin Semmelrogge, who did it for the director's cut.
* PropRecycling:
** The original set of the U-96 was later reused as the World War I submarine U-20 for ''Lusitania: Murder on the Atlantic''. Interestingly, the Type VIIC and Type U-19 submarines had similar internal dimensions.
** Creator/StevenSpielberg borrowed their full scale, floating replica of a German U-Boat, for ''Film/RaidersOfTheLostArk.'' This happened in the middle of filming, leading to a bit of a panic when some of the German crew who were not in the know woke up one morning and found the prop to be missing.
* ReferencedBy: In the ''Literature/Tempest2011'' novel ''Tempest Rising'', the half-mermaid Tempest swims deeper than she ever has before while looking for Kona. She remembers the scene in ''Das Boot'' where the submarine has to dive deeper than usual and springs leaks from the pressure, and hopes her body won't be damaged in the same way.
* ThrowItIn: To simulate the storm in the Atlantic, a model of the tower was splashed with water from a large tank. Actor Jan Fedder lost his grip on the railing and was washed off the model, breaking a few ribs in the fall, one of the other actors instantly shouted "Man Overboard". At first Petersen didn't realize it was an accident but [[AllPartOfTheShow enthusiastically yelled "Good idea, Jan. We'll do that one more time!"]]. Peterson still kept the scene and [[WrittenInInfirmity rewrote Jan Fedder's part in the film, so that his character spent a short portion of the movie in bed]]. The actor actually had to be brought back and forth from the hospital every day because of concussion. The painful expression on his face is real and not acted. (The scene which features him bedridden is available on the uncut edition.)
* WhatCouldHaveBeen:
** Creator/RutgerHauer was offered the role of the Captain, but he turned it down in favour of ''Film/BladeRunner''.
** When this was originally mooted as a German-US co-production, Creator/RobertRedford and Creator/PaulNewman were both considered to play the part of the captain.
** Several additional scenes were scripted based on the original novel, but in the end were never filmed due to budget and time constraints. In the original script, the U-Boat departs from St. Nazaire and docks at La Rochelle only at the end of the film due to heavy damage and an inability to reach its home port. The escape out of Gibraltar is also extended somewhat including the U-boat stopping a passenger liner and nearly sinking it, but at the last moment realizing the ship is of Spanish registry. The U-boat also encounters another submarine with an inexperienced crew at the entrance to La Rochelle harbor. The second submarine strikes a mine and the entire crew must be rescued. Finally, the character of Lieutenant Werner is much more heavily explored in the original script, including a love interest where Werner was seeing a French girl and by the end of the film suspected she was a member of the French resistance.
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