When the Professor and Stephanie are leaving at the end of the cruise, the Professor isn't wearing glasses, then while he's talking, the glasses are on his face. During the rest of the scene, his glasses keep appearing and disappearing.
the 'looking for husband' ad says Feista deck 132, but she is staying in PR 101, proven when Julie comes down there after seeing the ad.
The issue of Princess Prattle that features Dottie's personal ad also lists the itinerary for the Island Princess cruise ship. But this episode (and most episodes of this series) take place on the Pacific Princess.