Gary Cooper's tie is long and thin in the beginning of the luggage search at the border. It is tucked slightly into his trousers and has no tie bar. After one of the cuts to Dietrich, it is shorter and wider, and bears a tie bar.
When Tom catches up to Madeline at the border after she splashes mud over him while he's stopped to take a picture of himself, his car has far less mud on it than in previous shots.
When Madeline drives by Tom, who is stopped to take a photo of himself, she splashes mud all over him - and some of the water from the puddle lands on the lens of the film's camera.