This was the first time James Stewart worked with Spencer Tracy since appearing together in his debut feature film, The Murder Man (1935), in which he had a minor role and received sixth billing.
Spencer Tracy didn't want to do this film and, to keep him interested, James Stewart came up with the idea of a European crossing after filming, where they would travel across various countries. Tracy got really excited about this, so each day during filming they would make plans - Vienna first, then Berlin. Stewart himself started to get excited, and he would pore over maps. The last day of filming, Stewart went up to Tracy and said, "Spence, so when do we start the trip?" Tracy said, "What trip?" Stewart said, "You know, our great holiday, where we cross Europe." Tracy said, "Cross Europe? Why, I wouldn't cross the street with you, you son of a bitch!"
The destroyer that Spencer Tracy and James Stewart start their adventure on is a Fletcher Class Destroyer. The first was laid down in 1941 and the last in 1944; 175 were built. It was the first of the U.S. Navy's large destroyers during World War II; it also was the class with the largest number of units built. Most served in the Pacific theater.