The Japanese Sailor mentions Lloyd Bridges as being a famous movie star from before 1942. But Bridges's was primarily cast in unbilled or minor parts, and didn't become a star until well past the end of World War II.
The captured castaways are held in bamboo cages, supposedly booby trapped with grenades that would explode if the bars where pried apart. However, the grenades are clearly just hanging from wires like Christmas tree ornaments. Also the grenades are within easy reach, and potentially could have been taken by the prisoners to use against their captor.