Interesting coincidence that William H Macy, Lauren Holly, and the U.S.S. Swordfish also appear in Down Periscope (1996) as well.
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 U.S.S. 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.
The film was originally released through Artisan Entertainment under the title "U-Boat". However, another film with the same title had recently been released. The film was changed to "In Enemy Hands" after the film was purchased by Lionsgate.. "In Enemy Hands" received little or no publicity or advertising after being released in the U.S. by Lionsgate. Based on a true story, the lack of publicity and advertisement resulted in very little attention by movie-goers.