One of the survivors of the attack on the USS Indianapolis, Granville "GS" Crane, is portrayed by his grandson, Johnny Crane in the movie. GS Crane lost his arm to a shark while in the water after the attack. He is still living today.
Scenes set on the Portland-class heavy cruiser USS Indianapolis were filmed aboard the battleship USS Alabama. It is docked in Mobile Bay in Mobile, Alabama. This is the same battleship that was used to film the Steven Seagal movie Under Siege (1992).
This movie is based on the book titled "In Harm's Way: The Sinking Of The USS Indianapolis and the Extraordinary Story of its Survivors" by Doug Stanton. There is a 1965 movie titled "In Harm's Way" starring John Wayne and Kirk Douglas, which should not be confused with the book. The movie (In Harm's Way) takes place at the beginning of WWII - whereas the book is written about the events that occurred 3 weeks before the war ended.
Nicolas Cage's hand-prints have been enshrined in a reef object placed just offshore of Perdido Pass near Orange Beach, Alabama. The site, called "Posiedon's Playground", is a popular dive location created by David Walter.