As pointed out by Eddie Muller on TCM's "Noir Alley": When Ron Foster is coaching Pat Blair in the motel room on how to avoid the police, he pushes her out the window. She lands outside in a completely different dress.
When parking at the airport car rental parking lot, the car next to the fugitive couple is a 1959 Ford, but as they exit the car the car next to them has become a 1960 Ford.