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.
Pass the Vegetables, Please - S3-E3
Visible crew/equipment: As Mary Ann discovers she's blowing bubbles as she talks, you can see part of the device just to the left of her neck, and the bubbles can be seen coming from beside her left cheek.
Pass the Vegetables, Please - S3-E3
Continuity mistake: The compound of huts seems to be very close to the beach, as the Professor, Skipper and Gilligan look out and can see it. Other times, it's a fair distance away through the jungle and obscured.
Pass the Vegetables, Please - S3-E3
Continuity mistake: As the camera is close up on the radio, Mary Ann's hand is down on the table. In the wide shot, it's suddenly up holding a fork.
Continuity mistake: The bill referred to by Lovey when the Skipper and Thurston are arguing changes from stage money to a real one dollar bill, and back between shots.
Continuity mistake: As the rock that triggers the trap is pulled, the vine used slides completely off it. In the wide shot, the vine is securely around the trigger rock.
Continuity mistake: There are several shots of the island used in the series. In the opening, it appears small. In some inland shots it appears immense and mountainous, despite being described numerous times as a "tiny island somewhere in the Pacific."
Revealing mistake: Any time you see the vines used for different purposes, it's painfully obvious that they're very poorly disguised rope, such as the ones the Skipper and Professor use to rock the boat mock-up in the episode "Quick, Before It Sinks."
Gilligan's Personal Magnetism - S3-E21
Visible crew/equipment: Toward the end, the group is around the table, talking about Gilligan. Then they see a pear and a bunch of grapes float over to a plate at the head of the table. Skipper goes over and addresses the invisible Gilligan. If you look at the top of the hut, you can see the wires used to make the fruit float. Also, earlier in the hut with Ginger, when Gilligan bit the pear, you can see the wire holding the pear as it shakes after the bite.
Operation: Steam Heat - S2-E25
Continuity mistake: The professor wound the clock on the bomb by turning the hand to nine. A second after it was tossed in, it reads eight. It then takes about about fifteen seconds between the numbers to get to zero.
Gilligan Meets Jungle Boy - S1-E20
Visible crew/equipment: When Gilligan is floating inside the balloon and then outside, the wires supporting him are visible. (00:19:00)
Don't Bug the Mosquitoes - S2-E12
Character mistake: When the "Honey Bees" (Mary Ann, Ginger, Mrs. Howell) perform, Mrs. Howell (Natalie Schafer) messes up her lip-syncing throughout the number. But it is most noticeable at the very end when the girls put their heads together and say "buzzzzzzzzzzz" but Mrs. Howell is mouthing an "oooooooooo" which she changes to a "zzzzz" mid-way through the note.
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.
Splashdown - S3-E22
Plot hole: Most of the episode focuses on just Gilligan and the Skipper riding the capsule out to sea (although the Howells and the girls attempt to stow away with them at first). However the whole plot changes at the end... suddenly with nobody aboard the capsule, Gilligan tells the Skipper it floated off and Skipper yells at him saying "We could have ALL been on that capsule!" when it suddenly explodes thus saving everybody as if the plot now called for everyone to have been on board. It was still supposed to be Gilligan and Skipper only.
Plot hole: Many episodes show either visitors on the island swimming away or objects floating away on rafts (a lion, a silent film, etc) that at the end of the episode always make it safely to civilization (as heard on the radio)... yet, none of the castaways ever could swim or leave on a raft to attempt to get off the island and get rescued in the same way.
Plot hole: On many different occasions, the castaways meet a wide variety of people who say that they have been on the island for either ten or more years thinking they were the only ones on the island before the SS Minnow even arrived. With so many people who had been on the island for such an extended time, it seems kind of strange that none of them had ever met one another.
Pass the Vegetables, Please - S3-E3
Revealing mistake: When Gilligan is lifting the Skipper in the lounge chair, you can see the wires used to raise the chair up when the camera is close up on the Skipper.
Continuity mistake: When the imposter Gilligan is playing chess with Mr. Howell, the long shots show the imposter holding the spoon transmitter near the center of the table the chess board is on, whereas the close-ups show the transmitter close to the edge of the table.
Revealing mistake: After Gilligan lies down on his hammock, there is an "X" in the sand where actor Alan Hale, Jr. stands. Obviously it is the mark where Hale is supposed to stand, and he does stand there as he speaks to Bob Denver.
Continuity mistake: After the earthquake the skipper is holding the idol with both hands. The shot changes and only one hand is holding the idol.
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.