"The Screen Guild Theater" broadcast a 30 minute radio adaptation of the movie on January 25, 1943 with Mary Astor, Humphrey Bogart and Sydney Greenstreet reprising their film roles.
As the passengers debark in New York, there is a prominent shot of the Great White Fleet's head house. This was a real shipping company. It was, and is, the popular name of the United Fruit Company's shipping line. The title "Great White Fleet" in fact derived from the name given the United States Navy's main battle fleet which circumnavigated the globe in 1907-08. Painted white, the battle fleet must have been an impressive sight. The United Fruit Company's fleet was also painted white in order to help reflect the intense heat whilst operating in the tropics.
Director John Huston went off to join the war effort before the film was finished, and Vincent Sherman directed the final scenes.
Director Vincent Sherman met with John Huston just before Huston left the project to join the Army Signal Corps and shoot documentaries for the war effort. The two directors conferred just before they were about to shoot the scene in which Leland is trapped in the movie theatre and three assassins are trying to kill him. "How does he get out?" Sherman asked. Huston replied, "That's your problem! I'm off to the war!"
One of the Japanese is mentioned as a member of the "Kokuryukai", or Black Dragon Society. This was a nationalist Japanese organization, formed in 1901 to protect and develop Japanese interests, initially working against Russian expansion in Asia. In the US, during the Second World War, it became a convenient scapegoat for anti-Japanese propaganda and actions.
The film's original trailer copied the same format as the one for The Maltese Falcon (which had the same director and three of the same cast members), beginning with Sydney Greenstreet's face against an otherwise dark background as his voice narrated.
The last-minute screenplay change from Pearl Harbor to the Panama Canal was not implausible. Until the mid 1930s US military exercises concentrated on defending the Panama Canal from air, amphibious & small craft attack and were extensively covered by the press.
Though the film's plot was changed from Rick Leland foiling a Japanese plot to blow up Pearl Harbor to a Japanese plot to blow up the Panama Canal (necessitated when the Japanese actually attacked Pearl Harbor without Leland being there to stop them), the title wasn't, so the film is called "Across the Pacific" though the characters never even get TO the Pacific, much less across it.