Beauty Is as Beauty Does - S2-E2
Continuity mistake: They used a standard electric phonograph. Later on, the phonograph is a bamboo and wood device with a ship's wheel as the turntable. It had to be cranked like the old Victrolas to work.
Good Night Sweet Skipper - S1-E5
Revealing mistake: In the end scene, as Gilligan chases the bug, trying to quiet it, you can see the lines in the gourd where the hole will be after he hits Skipper with it.
Revealing mistake: As the gale force wind lifts Gilligan, you can see the outline of the harness under his clothes and can make out the wires holding him up.
Continuity mistake: In this episode, the damage to the boat is different than seen in "Two on a Raft." Also, there was a vessel number on the bow of the boat that is absent in this episode.
Revealing mistake: When the shark takes a second bite of the raft, you can see the bite before it's taken.
Continuity mistake: When Skipper tries on the sheet to teach Gilligan not to be scared, we see him putting it on and it is solid white. However, when Gilligan says he isn't scared he says it is because a "ghost doesn't wear a sheet that says S.S. Minnow on it." Now the sheet has wording on it. (00:08:45)
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.
Little Island, Big Gun - S1-E18
Visible crew/equipment: Gilligan shoots a bag of money in a tree with an arrow. As the money falls to the ground you can see a fan in the lower left corner of the screen aimed up towards the tree.
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.
Pass the Vegetables, Please - S3-E3
Continuity mistake: While Mrs. Howell cleans the hut at maximum speed, the book Mr. Howell reads changes position as the scene cuts.
Continuity mistake: As Rodriguez goes back to Ginger, the Skipper straightens his hat. In the closer shot, Skipper straightens his hat again. (00:09:55)
Continuity mistake: As Mr. Howell tells his story, the table Ginger is on rocks to the point the canteen beside her falls off. A second later, she's drinking out of it.
Visible crew/equipment: As the camera looks at Skipper and Gilligan, after the tossing of the sail, the edge of the studio tank is visible for a few seconds in the background.
Continuity mistake: After the shark bites Gilligan's paddle and he holds it up, the amount of wood between the handle's connection and the bite differs from shot to shot.
Factual error: The portable radio is an AM band only, therefore there is no need for the external telescoping FM antenna.
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.
Good Night Sweet Skipper - S1-E5
Revealing mistake: At the end, when Gilligan is holding to gourd up, chasing a fly, the lines of the cut out spot for the final gag are visible.
Revealing mistake: The beam the Skipper wants Gilligan to work on is six feet, but if you look carefully, the beam is already pre-cut.
Plot hole: How could it be that every time someone or something was visiting the island during many episodes, they always made it back to civilization by the ending scene (as heard on the radio)? I can understand an actual person, but once anything else (such as a lion, a movie reel on a raft, etc.) leaves the island, it arrives perfectly by just simply slowly floating on the water with no human to guide them. Maybe the one exception could be the robot (programmed by the Professor).
The Friendly Physician - S2-E29
Other mistake: The whole time the control for the booths is operated, the handles are pulled towards the camera. In the final lab scene, Gilligan flips the lever towards the camera, but you can see the indicator reads 'OFF'.
Answer: Bob Denver answered this when he was on a talk show hosted by Pat Sajak. He said they were going to write into an episode where the castaways found all these clothes, but it got too complicated, so he said, they decided, "who cares, it's only a TV show," and forgot about it. So the writers and actors even asked this, they just never bothered to address it.