At the Charles' apartment, Asta reaches into the fish bowl for the rock, then a moment later, Nora picks him up and he is completely dry.
When Nick is being mobbed by the reporters after getting off the train, the reporter talking to him stumbles and has to step over Asta's dog leash. Immediately after that he is shown standing behind Nick's arm and the leash.
When Dancer sees that Nora is going to use the pay phone (in the Lichee Club), he approaches the hat check girl to load her up with coins so that she can keep Nora from using the pay phone. When Dancer first approaches, the hat check girl is standing at the counter with a blond hat check girl. When Dancer arrives, she's now sitting in a chair, facing toward Dancer.
At their "Welcome Home" party, Nick and Nora dance across the living room to the kitchen. When Nick is in the living room and pushes the door open, his hand is empty. When he and Nora go through the door and step into the kitchen, he has a cocktail glass in his hand.
When David is at home three small lights and a large one can be seen in the window. However in the following cut when Nora walks in there are now two small lights and a large one. Then when Polly's brother appears in the window, it goes back to the original four lights.
As the train is arriving in San Francisco at the start of the movie, the rear-screen exterior is backward. Notice the lettering on the buildings.
In the very brief shot of the divers underwater looking for the gun, one can see air bubbles going into their diving helmets - that snippet of film was run backwards.
As Nick shines his pen-light on the names outside the apartment building, the light falling on the wall is out of sync with his movements.
After the scenes when Selma Landis (Elissa Landi) is arrested, there is a transitional scene featuring several newspaper headlines about the case. One of the papers, shown as the San Francisco Chronicle, bears the upper-left front page motto "All the News That's Fit to Print." This is the world-famous motto of the New York Times, adopted by publisher Adolph Ochs and first used October 25, 1896.
When Nora arrives at the janitor's building; Abrams turns around and heads to the entrance door to let her in. However, there was no way of him knowing that she was outside the door since he had his back turned to the door and no one rang a buzzard nor knocked nor did anyone say anything.
When Nick and Abrams go to the hotel looking for Polly's brother, the desk clerk tells them he is in room 212. However, when we see them open the door to the room, the number on the door is 221.
When Penny Singleton is doing her number with all of the dancing girls, just before the girls come out, she backs up into the bandstand and almost falls backward.
When the train is pulling into the station, the reporters ask where Nick Charles is. Two different trainmen in two different cars both say "Two cars back."
At about 1h 10min., when Nick and Nora are talking in the kitchen, a power cord is plugged in behind them. The shot changes to a closer view of them, then when the camera goes back to the longer view, the cord is unplugged.
When Nick arrives at Polly's building; he was dropped off in a taxi and he instructed the driver to wait for him. The telephone number on the taxi read Tuxedo 1234. However, much later on, when the various suspects are brought to the building some are shown exiting from a taxi with that same telephone number. Chances are that the film company used the same car.