You can find this slipup in the episode where they

investigate Giant Squids and Cannibals.In the part where they're talking about Jules Verne's novel 20,000 Leagues Under The Sea,they claim that in the novel a mysterious sea monster is terrorizing ships all over the world,and Captain Nemo and his crew go to find out more about the sea monster,which turns out to be a Giant Squid.Let me clear some things up for you.True,in the novel there is a mysterious sea monster terrorizing ships across the world,but the monster is NOT a giant squid.A french scientist named Pierre Arronax has a theory that the monster is a giant Narwhal.He goes on an expedition to find out more about it but it turns out that the "monster" is really an advanced submarine whose captain is a sea explorer named Captain Nemo who has retreated from the surface world and lives in the ocean.After Pierre dicovers Captain Nemo's secret,he is forced to live with Captain Nemo on hissubmarine,Nautilus. There is a famous scene in the book where the Nautilus is attacked by a pod of Giant Squid,but it's just one scene!It's not the point of the book!I swear,Jules Verne must be rolling in his grave!