Trivia: Twenty Thousand Leagues Under the Sea

Book Version
  • Executive Meddling / What Could Have Been: Verne originally wrote Nemo as a Polish nobleman, who lost his family to the Russians. Verne's publisher was wary of portraying the Russians (France's ally at the time) in a negative light, and didn't want to lose sales in Russia, so he persuaded Verne to make Nemo's nationality a mystery note . Also an example about Tropes Are Not Bad: Revealing Nemo's Back Story left him only a menace against a single nation, but leaving Nemo's nationality anonymous not only defines him (Nemo means Nobody) but also makes the reader realize that any nation, even the reader's nation, could have committed the alleged crimes against Nemo and his family. Even more, it implies that no ship of any nationality was safe for navigation. The new backstory also approved to many readers, lent Nemo more sympathy and recent adaptations have pretty much embraced the image of Nemo with a turban and an awesome beard.
  • Science Marches On:
  • Technology Marches On: Electricity was imbued with almost magical power, and a lot of the technological wonders Verne describes seem downright quaint to modern eyes. Still, credit where credit is due, he did get the fundamentals of how submarines would work in the future essentially right.
    • The Nautilus was supposed to make 50 knots on Bunsen batteries. The only modern submarine which could approach 50 knots needed 30 000 kW for the main engine. To get 30 000 kW from Bunsen cells their combined size would exceed Nautilus entire hull in size by a few orders of magnitude.
    • Also, an in-universe example of Schizo Tech: despite the usual rotating electric motor with brushes being known and used in the 1860s, Nautilus main engine is an oscillating electric motor ( "where large electromagnets actuate a system of levers and gears that transmit the power to the propeller shaft") - less efficient and a royal waste of space.
    • The new technology of double hull seemed to solve most problems in an age when most vessels were still wooden sailing ships, so Verne become enthusiastic about Nautilus double hull able to withstand the pressure "in the deepest ocean trench". No double hulled submarine can go below 1300 meters, specialized deep-diving vehicles are small craft with 5-inch thick shells.
    • Nautilus crew diving suits are an autonomous version of the heavy helmet of Verne's lifetime, yet all these had been used only to very shallow depths. To use them hundreds of yards deep with no decompression stops would only make the divers succumb to decompression sickness. Illustrations, including the original's, however, show them as having air tanks rather than tubes that could break.

Film Version
  • All-Star Cast: A first for a live-action Disney film. James Mason as Nemo, Kirk Douglas as Ned, Peter Lorre as Conseil, and Paul Lukas as Arronax.
  • Age Lift: Arronax and Conseil are played by actors much older (Lukas was 59 and Lorre 50 at the time) than their book counterparts, who are respectively 40 and 30.
  • Fake Nationality: Arronax is French, and Paul Lukas is Austrian-Hungarian-born.
    • The same goes for the German Peter Lorre, who plays the Flemish Conseil.