Gilligan tries to teach himself to surf and practices standing on a board in the lagoon. He ties his feet to the board, then tips over so that he is completely submerged under the surfboard. The Skipper comes to rescue Gilligan and wades into the lagoon up to his ankles, but his pants are already wet up to the middle of his butt; however he's dry from his waist up while he uprights the board so that Gilligan can breathe. As the camera cuts from Gilligan to the Skipper, the Skipper is now completely wet from head to toe although he never submerged below the water's surface.
Duke guesses that he was on his surfboard for 4 or 5 days before landing on the island. He had nothing with him so he would not even be alive because the human body cannot survive more than three days without fresh water.
The Professor pronounces the name of the capital of South Dakota (Pierre) as "Pee-air", which is incorrect. The correct pronunciation is "Pier".
Mr. Howell states that World War I was started by a duke. This is not accurate, as it started with a duke--Archduke Franz Ferdinand--as the victim of homicidal fanatic Gavrilo Princip. So it is Princip and not the Archduke who should get the blame for this war.
When the Howells meet Duke, thinking he's an aristocrat, address him as "Your Highness". The correct address is "Your Grace".