When Arnold is getting ready to head to the airport, he puts on a dark tie with small stars. When he sits on the airplane, it is a totally different tie.
Several times Kay is seen making Arnold's breakfast. She fries one strip of bacon and cracks one egg into the frying pan, yet there are two eggs on Arnold's plate one morning.
When Kay is upset and walks through the rain, her hair is wet and a mess. When she walks into the bar, she runs her hand through it quickly, and by the time she sits down (a matter of seconds), her hair is dry and all in place.
In almost every exterior scene of Kay and Arnold's house, there is a Buick sedan and a Subaru station wagon parked in the driveway in front of the garage. However, when the taxi picks up Kay to take her to the airport and drops Arnold and Kay back from the airport, the cars are not in the driveway. It was suggested that since they were going out of town they might have moved the cars into the garage, but when Kay leaves it is unknown, even to Arnold himself, if he will accompany her.
When Kay gives the leaflet to Arnold at the breakfast table, the first camera angle shows him folding the paper and placing it on the table. Then it cuts to another camera angle, and Arnold is folding the paper again.
(at around 15 mins for the first time and multiple times later) Kay breaks the fourth wall and looks directly into the camera.