When first seen, the sub chaser has the number 592 on its hull near the bow. But when aboard, looking up at the crows nest, the number 590 is observed.
The narrator states that the model for the Mona Lisa was one of painter Leonardo Da Vinci's girlfriends. The model was, in fact, Lisa del Giocondo, the wife of one of Leonardo's patrons. Historians believe Leonardo was gay, so it's unlikely he had any girlfriends.