Not only does Robert Vaughn (who played "Napoleon Solo" on the TV series The Man from U.N.C.L.E. (1964) appear in a cameo at the party, but there is a snatch of "The Man from U.N.C.L.E." theme heard on the soundtrack when Paul Lynde goes undercover in drag.
The original Glass Bottom Boat did not sink. It remains to this day in a modified dry dock on Catalina Island, off the California coast. In 2006 a paddle boat named the Phoenix sank in 800 feet of water off Zuma Beach in California. For some reason this sinking had been incorrectly rumored to be the original Glass Bottom Boat; the Nautilus. The Nautilus can still be visited on Catalina; but it's not a marked attraction. Locals can usually tell where the boat is being kept when asked.
Many people mistakenly think the boat used in the film sank two miles off the coast of Zuma Beach in Los Angeles on 11 June 2006. The boat the sank--The Phoenix (and NOT The Nautilus, from this film)--was traveling from Newport Beach to San Francisco Bay, where it was going to be used as a Cajun restaurant. The cause of its sinking was due to a 2'x6' crack in the glass hull. All crew were rescued. What made the sinking unusual is the glass bottom which was installed at the bottom of a "well" in the center of the ship. The top of this well is set above the usual waterline so that if the glass broke, as here, the ship would not sink.