Deliberate mistake: In the scene where Marie is trying on shoes, a pair of powder blue high top Converse sneakers can be seen next to her feet. It must have been done intentionally, but since there is no trace of modern apparel anywhere else in the film (the closest would be the mere mention of hot pink dress fabric but, as it's not shown, we don't know what exactly Marie calls "hot pink") these shoes (and the fabric) can't be considered part of a thematic element or artistic license. (00:55:35)
Deliberate mistake: After takeoff, an exterior shot of the plane switches from a Boeing 757 to an Airbus A320.
Deliberate mistake: During the scene on the train in lounge car, a picture on the wall prominently shows an ALCO PA locomotive. The movie was set in 1945, but this locomotive was first produced in 1947.
Deliberate mistake: At or near the beginning there is a scene with autumn leaves. The colours and amount are just not consistent with the date of September 11. They seem to be about 3 or 4 weeks ahead of schedule.