There were constant struggles between Miriam Hopkins and Edward G. Robinson during the shooting of the movie. She constantly changed her lines and tried to upstage and unsettle Robinson's performance. After two weeks they had to shoot a scene where Robinson had to slap his co-star. He did just that, but put such force in it that she fell to the ground. After a pause the crew began to cheer, fed up as they were with Hopkins' antics.
The famous uncredited early David Niven appearance can require several viewings to spot. It is about twelve minutes into the film, as Mary is led along the street and Old Atrocity (Walter Brennan) says "Make way for a lady!". Niven, wearing a peaked cap with a coat over his left arm, says in his best Cockney accent: "Oright- oright!" and something about bars in Africa, as he leaves the saloon with the main group in front of him.
Colonel Cobb quotes from lines 92-3 of 'The Launching' by Henry Wadsworth Longfellow (1807-1882): 'She starts, she moves, she seems to feel / The thrill of life along her keel"
The $50 that Old Atrocity demanded to row two passengers from their ship to shore before doubling the price en route would be the equivalent of $1998 in 2023. Jim Carmichael's gold earnings of $40,000 in 1849 would be a substantial $1,6 million in 2023, making his cavalier attitude over its loss a bit unrealistic.