In a 1975 interview (available on YouTube), John Frankenheimer considered this as his worst film; he called it "lousy" and admitted that he made it because he needed to pay for his divorce.
The Narrator throughout the film is Dick Wesson (not the actor Dick Wesson). He is best known as the announcer for Le monde merveilleux de Disney (1954) from 1954-71, as well as many Quinn Martin series. Wesson was also the Narrator for Disneyland's extinct attraction, America the Beautiful in Circarama.
The ship that stands in for the Japanese cruiser in the finale is the USS Canberra (CA-70). Originally a WWII Baltimore-class cruiser, she was converted into a Boston-class guided missile cruiser in 1952 and was the first US Navy warship named for a foreign capital city. She is shown without any RIM-2 Terrier missiles on either of her aft twin launchers. She was decommissioned on February 2, 1970, stricken from the Naval Vessel Register on July 31, 1978, and ultimately sold for scrap in 1980.
According to David Niven the film was originally going to be made in the studio, then at the last minute director, John Frankenheimer decided to make it in Mexico in a rough location in the jungle at Quatsicorpos, which meant daily mile-long journeys up river. One day one of the boats hit the wake of one of the others at an angle tipping everyone into the river, fortunately without any mishap, and all were rescued from a sand bank.