Languages

It was usual for Italian films to be entirely post-synched even if all actors were speaking Italian. This may star two English speakers but it was an Italian film so it was post synched in Italian as per normal.
Even so, I agree that it might have made sense to prepare an English Language dub given the stars, but it is much cheaper to subtitle so maybe they thought there wouldn't have been enough international cinema and TV sales in English speaking territories (pre-home video don't forget) to justify the extra cost. In non-English speaking territories the film would have to be dubbed or subtitled in the local language anyway.