In the belly of the ship, David lights a match. In one shot, the match is burnt almost in half. In the next shot, it is a newly-lit match.
When Maria shows David a globe, David asks her to show him Denmark. The camera focuses on Denmark, then traces down the globe to Italy. Though antique in appearance, modern country names on the globe (Czech Republic, Slovakia, Bosnia) shows it dates at least from 1993.
In the window of the Italian bookstore, the book on display next to the book the protagonist is looking at, is clearly, "Cieli e mari: le grandi crociere degli idrovolanti italiani (1925-1933) / Ranieri Cupini". The first edition by Mursia was in 1973, long after the events in the movie.
The radar installation at the airport where David departs is clearly more modern than one that would appear in 1952.
When David is about to board the flight to meet his mother, we can see the tail of a modern airliner that is taxiing in the background.
In the window of the Italian bookstore, there is a book on display "L'uomo che guarda" of the Italian writer Alberto Moravia. This book was written in 1985, long after the events in the movie.