Millie drives a red roadster (with a drugged Mr. Graydon beside her), chasing the the laundry truck. As Millie makes a right turn from a T-junction, a modern blue-grey station wagon can be seen parked on the top left side of the intersection.
Jimmy Smith's boss' "red roadster" is a 1925 Pierce-Arrow Model 80. The Model 80 was manufactured by Pierce-Arrow for the 1925 through 1928 model years, when it was superseded by the Model 81. No Model 80 Pierce-Arrows had been manufactured in or before 1922, when this movie was set. Unlike most brands of automobiles at the time, the headlamps of Pierce-Arrows were installed in fender-mounted moldings.
In an early scene, Mrs. Meers wheels her laundry cart into the elevator, punches the elevator button, pours chloroform on a rag, and then, after knocking out Ethel Pease, returns with her cart to the elevator. Sometimes she is wearing gloves. Other times, she is bare-handed.
There is a close up scene where Jimmy helps both Millie and Miss Dorothy off the wing of the plane onto the ground. In the next scene when Muzzy is driving up to the plane, Jimmy is once again helping Millie off the wing of the plane onto the ground.
When Millie is about to drive away from the hotel with Trevor Graydon, she is wearing a black and white checkerboard hat. In the next shot as she is actually driving away, the person behind the steering wheel is not wearing a hat. In the next shot, she is once again wearing the hat.
Mrs. Meers is injecting a red apple using a syringe with a clearly visible needle. When Miss Dorothy arrives and Mrs. Meers thinks that Miss Dorothy might catch her injecting the apple, she quickly tries to hide the apple and syringe under the desk. The scene shows no needle anywhere.
When Millie and Muzzy are on the swing talking about how Muzzy met her husband, the two are sitting closer when the scene is shot over Millie's shoulder facing Muzzy than they are when the scene is shot over Muzzy's shoulder facing Millie.
During the "Babyface" dance, Millie loads paper into the type writer with a couple of inches sticking above the roller. When it switches to showing the typewriter from her perspective as she types, the paper is gone. When it switches back to the wide shot, the paper has returned.
When Muzzy sings lower and lower notes it causes a martini glass to break suddenly. But glass is broken by its resonate frequency - the note it makes when it's rung by tapping it sharply. A much higher note than Muzzy's is needed to break a martini glass.
When Jimmy and Millie are sitting on the ledge outside the office, the flagpole which both fell onto a few moments before is nowhere to be seen. That's because they have come off the flagpole onto a ledge well below it.