Other mistake: Ginger keeps hoping that the play will help her be discovered. But according to what we know, she's already a famous movie star.
Other mistake: The Communal Hut is built in the clearing, and has a dirt floor. When Skipper and Gilligan check outside, it's floating in the lagoon. But that suggests it had a wooden floor.
They're Off and Running - S1-E29
Other mistake: In several shots during the first turtle race, Gilligan is inexplicably wearing a wedding band (Bob Denver was married to his first wife at the time and forgot to remove it). (00:01:00 - 00:03:00)
Other mistake: Where Gilligan is yelling to everyone "Don't get on the minnow, the glue won't hold!" you can see a pack of Chesterfield cigarettes sticking out of his left front pants pocket.
Other mistake: When the headhunter is about to chop a tree Gilligan is behind, he yells. The actor has metal fillings in his teeth. Headhunters would not likely have a dentist.
Other mistake: As the girls are trying to land their catch, the Skipper comes by and starts to help. Although he was walking by, when he starts to help, his pants legs are already wet from previous takes.
Other mistake: At the beginning of the episode when the Skipper wakes up on the boat this scene is actually from the original pilot, as you can see the 3 different actors that played the part of the professor, Ginger, and Mary Ann. (00:01:20)
Suggested correction: The original actors ARE shown, true. However their characters slightly differred in the original pilot. They were known as a high school teacher, Ginger, and Bunny.
The Return of Wrongway Feldman - S1-E25
Other mistake: As the plane taxis in, there are tracks from the wheels in the sand prior to the plane's entry into the scene, showing a previous take.
Other mistake: As the Skipper is on the ground under the tree waiting for Ginger to get Gilligan, the headhunter is crawling behind him. You can see some smoke in the lower left corner, likely cigarette smoke from a crew member.
Other mistake: As Mary Ann pedals to power the sewing machine, the bobbin only clicks back and forth, giving the illusion of real movement.