As Anthony Wayne and Suzanne are deplaning in Geneva, the airplane in the background, that they got off, is not one in which we see them land.
When Stefan takes Nicole back to his house, they enter a dark room upstairs. The light coming in through the French doors goes out a couple beats before he turns on the lights in the room.
In a close-up of Stefan's letter near the end of the film, Nicole's matte fingernail polish does not cover her cuticles. But a minute later, when she embraces Tony, her fingernails are fully covered with shiny polish. The close-up likely used the hands of a stand-in actress.
The shot of the airplane landing at Geneva is reversed by the backwards letters of the plane's registration on its side.
When Stefan meets up with Nicole at the charity event, a shadow of the boom microphone is visible moving on the wall upper left in the frame.