When in Rome, Peter and Lois go down a canal on a gondola, there are no canals or gondolas in Rome, they are in Venice .
Lois tells Peter that she bought tickets to the "grand opening of the biggest water park in all of Rhode Island." Peter should have known that they were going out of state since they are on a plane & already live in Rhode Island. There was no need to get on a plane. But then again, Peter is self proclaimed "retarded" as stated in an earlier episode.
Peter and Lois visit a football (soccer) stadium in which Peter uses 20000 fans to display a message to Lois. Despite the episode being set in Italy, the stadium is quite clearly the camp nou, home of FC Barcelona in Spain.