So I got curious and decided to see how close to real life the story of U-234 was. While obviously the stuff about the secret painting was made up, the real U-234 was in fact heading toward Batavia, or at least in that general direction, and did have Japanese officers on board. The real U-234 was tasked with transporting German liaisons to Japan and some Japanese liaisons back home, along some something a lot more valuable than a painting; Uranium Oxide, enough to make 20% of the enriched uranium for a bomb. In real life though, the Germans surrendered while the ship was still in the Atlantic and the captain surrendered to an American destroyer escort.