Revealing mistake: Near the end of the episode, all the castaways are passed out cold when Lord Beasley finally catches his butterfly. Right after saying the line "That's the trouble with you Americans - you simply don't know how to hold your tea" as he's exiting off camera, Mrs. Howell starts to open her eyes slightly, but then quickly shuts them again. Perhaps she thought the cameras stopped rolling.
Our Vines Have Tender Apes - S3-E20
Audio problem: Towards the end of the episode, the castaways read Tongo's note that he can't take them back with him due to how he behaved with the gorilla. Mr. Howell yells "we won't tell anyone!" followed by other random comments from the others for Tongo to come back. Tongo leaves and as the camera pulls away from the castaways, the same audio repeats itself even though this time doesn't match what anyone is saying.
And Then There Were None - S3-E13
Continuity mistake: Whenever one of the castaways falls in the trap and "disappears", there is complete silence when their name is called out, yet when the Skipper falls in (the last of the six), suddenly Gilligan hears all their voices shouting from down below.
Gilligan's Personal Magnetism - S3-E21
Continuity mistake: When Gilligan knocks the door off the hut it lands on the Skipper's neck with the life preserver on the top. In the next shot the preserver is on the bottom.
Pass the Vegetables, Please - S3-E3
Other mistake: After Gilligan gets up to take the sand to Mary Ann, the camera closes in on the box lid. After it does, the picture goes into a freeze frame because the ripples in the water of the lagoon stop dead still for the few seconds until the dissolve into the next scene.
Pass the Vegetables, Please - S3-E3
Continuity mistake: The radiation meter the Professor reads disappears between shots.
The Producer - S3-E4
Continuity mistake: Harold Hecuba (a.k.a. H.H.) goes out to change costumes. When he comes in as Ophelia the stage door first closes behind him, then falls off the hinges. The shot cuts to the Castaways, then back to H.H., and the door is back on the hinges.
Pass the Vegetables, Please - S3-E3
Revealing mistake: When Gilligan tosses the coconut, as it flies past the Skipper, the line it slid on catches the light as it shakes.
Pass the Vegetables, Please - S3-E3
Revealing mistake: After the Professor puts everyone to sleep reading the book, the camera backs up, showing the straight seams of the soundstage floor where the set ends.
Pass the Vegetables, Please - S3-E3
Continuity mistake: The book the Professor is reading to the others immediately switches from being lower to higher as the scene cuts.
Pass the Vegetables, Please - S3-E3
Revealing mistake: The guide wire used to "throw" the coconut through the hut by Gilligan is visible.
Revealing mistake: In the dream sequence, the boss, E.V.I.L., is bald. You can see the line of the skin wig he has on.
Lovey's Secret Admirer - S3-E19
Other mistake: At the end of the episode when Gilligan is using the lie detector he says "I love spinach." The lie detector said it was a lie. But in the episode "Pass the vegetables please" spinach is his favorite vegetable.
The Hunter - S3-E18
Revealing mistake: As Gilligan sits in front of a large boulder, the disguised charge that simulates a bullet strike is easily seen.
Continuity mistake: After the vampire's wife (Ginger) unfolds the couch bed, she laughs with her arms down and spread out by her sides, but the next shot shows her hands up by her face, clutching her gown.
Topsy-Turvy - S3-E10
Other mistake: At the end, after Mary Ann puts the pie down, and Gilligan drinks the juice, he hits the table, flipping the pie into the skipper's face. First, the Skipper starts to wince when Gilligan hits the table, preparing for the gag. Second, the pie tin defies physics by staying exactly in place on the board after the pie leaves it, and after the board bounces once and settles down. Third, Gilligan dips his finger directly into the cream on the Skipper's face, rather than missing a few times.
Topsy-Turvy - S3-E10
Continuity mistake: As the Professor cautions Gilligan about hallucinations, the long table is visible through the door. When the camera is close to the Professor and Skipper, the table is gone.
Topsy-Turvy - S3-E10
Continuity mistake: When Gilligan looks at the papaya tree, the fruit is yellow. When he gets to the tree, the fruit is green.
Continuity mistake: When Balinkoff shows Gilligan the control computer, it is off, but Gilligan is under control. A moment later, it is on.
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.