When Taddeo borrows three books from Beatrice, presumably in a public library, the volumes of the series 'Classici dell'arte'--which didn't start until 1966--are clearly visible on the shelf in the background.
At minute 23:16 a modern white car could be seen reflected in 1954 shop widows.
At minute 6:10, when Manuelo exits from the lingerie shop, you can clearly see, under the city porches, modern dressed people and staff watching the scene from behind a plastic tape.