In the first scene in the bar, in which all are listening to the NBC Radio program "Information, Please", the dial of the AM radio on the shelf behind the bar changes location between long shots and close-ups. It is correct in close-up, at 660kHz, one of the broadcast frequencies NBC used in New York City in the 1940s, and at 880kHz in long shots, the frequency of the New York City CBS affiliate.
When Tess gets out of the car as she arrives at her parents' house, she shuts a car door and you can see the reflection of man's legs standing and watching, even though there's no one else in the scene.
In the kitchen scene Tess (Hepburn) uses a vacuum coffee maker (Cona) to make coffee. But if she had put the coffee in the bottom of the coffee maker and the water in the top, as she is shown to do, it wouldn't have made coffee at all. It might even have exploded.