In the beginning, the two actors were shown in a closed plane side by side. When the plane was shown flying in a long shot, it was a open plane with the actors not side by side.
In the final football game, the clock on the scoreboard shows the time approaching the last minute of play twice.
When Steve leaves the hotel room with Harry's letter to Maizie in hand, he turns off the lights by a light switch at the door. The lights go out well after the "click" is heard and his hand is well away from the switch.
Although supposedly in Chicago, Harry and Steve race past the United Artists Theater on South Broadway in Los Angeles while in a taxi on the way to the airport.