When Lucy is having one of her tantrums, a sheet of newspaper drifts down from the ceiling behind her. Apparently, she had tossed the paper she had been holding a moment earlier into the air, but that gesture ended up on the cutting room floor.
As Lucy James (Virginia Bruce) finishes singing "I've Got You Under My Skin," she has a lit cigarette in her right hand as she reclines on the settee. The camera angle changes, but now the cigarette has suddenly changed to a glass of champagne.
James Stewart and Eleanor Powell are supposed to meet at 22:00 sharp at Central Park. While he is in the club with Virginia Bruce, he looks at his watch and the time is 23:15. At the same time, Eleanor Powell who is waiting alone at Central Park, looks at her watch and the time is 21:00.
When Nora and Jenny visit the submarine and are talking to Gunny Sacks and Tex Baker, the same ship can be seen passing at least two times.
Gunny Saks is visible on the sub's sail, despite being in the brig, where he is visible in the following scene.
The interior of the submarine during the opening musical number is more than twice as wide as a real submarine would be.
Diesel submarines traveled on the surface except in time of war. They were much faster on the surface since they could use the Diesel engines rather than run on the batteries.
In the extended Central Park scene where Jimmy Stewart and Eleanor Powell sing "Easy to Love," there is a statue of Abraham Lincoln in the background. No statue of Lincoln exists in Central Park: there is one in Union Square. The statue used in the movie is a facsimile of the "Standing Lincoln" which has resided in Lincoln Park, Chicago since 1887.
Immediately following the credits there is a periscope in the distant water. When the scene cuts to a close-up, a shadowy human figure is clearly holding the periscope just under the water in what actually appears to be a pool.
The opening scene is set aboard a submarine entering New York Harbor while submerged at periscope depth. Her skipper would have brought her in while surfaced - the risk of collision in a busy port is substantial.
When Ted gave Mr. McKay Nora's phone number, he never provided Mr. McKay with a name for the "best dancer in the world." Nora's roommate was also a dancer previously.