In Enemy Hands
- The U-429 is a real boat that was made by the Germans in World War II but was transferred to the Italian Navy after being produced. The boat however never saw combat.
- The real USS Swordfish was lost with all hands in the waters around Okinawa. The real U-429 was transferred to the Italian Navy (where it was dubbed the S 4), then served as a training boat for the German Navy following Italy's surrender.