Pass the Vegetables, Please - S3-E3
Revealing mistake: As the camera pulls back from the hut, the bubbles can be seen coming from around the edges of the shot.
Pass the Vegetables, Please - S3-E3
Revealing mistake: As the Professor reads his meter, the bubbles are shooting from beside his nose, rather than his mouth.
Pass the Vegetables, Please - S3-E3
Other mistake: The spot where the coconut Gilligan tosses goes through is rounded, the suddenly squared in the close up. The wall in general is differently colored than the rest of the hut.
Pass the Vegetables, Please - S3-E3
Revealing mistake: When Gilligan picks up a coconut, the first one he crushes easily is totally different than the ones in the pile it's on, showing it was a specially made prop.
Pass the Vegetables, Please - S3-E3
Audio problem: As Gilligan gets up to lift the stool he was sitting on, we hear the sound of wood scraping on the floor, but it's on sand.
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.
Continuity mistake: Between the time the Professor is put into the trance and waking up, his mouth mouth goes from agape, and head turned to the left, to mouth closed, facing forward.
Continuity mistake: The professor is put under a trance, referred to as "zombiefied." When it first happens, the professor is looking to his left. Later on, he's looking straight ahead.
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.
Other mistake: On the beginning, the butterfly Beasley calls the Pussycat Swallowtail is yellow. Later it's orange. Also, when Beasley holds the cage with the painted butterfly, you can see the wires making the puppet move.
Hair Today, Gone Tomorrow - S3-E8
Revealing mistake: After Skipper goes bald, you can see the line of the skin wig on him.
Hair Today, Gone Tomorrow - S3-E8
Revealing mistake: When Gilligan is bald, you can plainly see the line of the skin wig, as well as able to see his hair under it.
Continuity mistake: When Balinkoff shows Gilligan the control computer, it is off, but Gilligan is under control. A moment later, it is on.
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.
Topsy-Turvy - S3-E10
Factual error: When looking at the machetes the headhunters had, you can see the molded plastic handles on them. The natives wouldn't have access to such things.
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.
Revealing mistake: After the Skipper throws the attache case in the lagoon, it explodes. Problem is that the lagoon water and the water with the explosion are in two different areas, and where the explosion is, there was no case floating. Just markers floating where the explosive is placed underwater.
Visible crew/equipment: As Gilligan runs along, stuck in the hollow log, the wires holding it up and guiding it are visible toward the top of the shot.
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.