Continuity mistake: As Gilligan marches over the cliff, he's wearing Skipper's hat. As he's hanging on the branch, his regular white hat is on his head.
Don't Bug the Mosquitoes - S2-E12
Other mistake: The 4 band members, all their equipment, months worth of food supplies, I am assuming medical supplies, change of clothes and other sundry items all magically fit into a small two seat helicopter.
Audio problem: As Gilligan is carrying Kona, there is an earthquake and coconuts fall on him. However there is the sound of eight hits, but only four hit him. Also, there's the sound of a hit, but there's no coconut near him.
Voodoo Something to Me - S1-E4
Revealing mistake: While searching in the jungle, Gilligan slips and goes down a slope. As he gets toward the bottom, the plastic sheeting used to make the slide ripples.
The Friendly Physician - S2-E29
Continuity mistake: The color of Ginger's shoes are different once returning to the island at the end of the episode from what she wore on the mad scientist's island.
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.
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.
Castaways Pictures Presents - S2-E7
Plot hole: During all their filming for their "silent" movie, the castaways are using talking in actual dialog to explain their overall situations on the island, but when played back at the end, it's just showing them all talking sped up without hearing voices being a silent picture. What was the point of them filming then with actual words? They may as well just moved their mouths randomly without actual words coming out. In addition, where did the "music" come from throughout the movie?
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.
Visible crew/equipment: As the flame is blown out by Skipper's sneeze from behind a board held by Gilligan, you can just see a man from Skipper's left blowing it out.
Visible crew/equipment: As the Skipper makes an 'X' in the dirt, the shadow of the camera rig raising up is seen on the ground.
Good Night Sweet Skipper - S1-E5
Continuity mistake: When the Professor drops a couple of tranquilizer pills in the Skipper's cup, it's nearly filled to the rim. As he hides the bottle of pills, the liquid is a little lower.
Voodoo Something to Me - S1-E4
Continuity mistake: As the Professor comes up to Skipper and the girls, his left hand goes up to his face, but a second later it's his right hand on the bridge of his nose.
Visible crew/equipment: As Wrongway says "A couple more minutes, I could've been killed", the studio lighting is reflected on the left lens of his goggles.
Continuity mistake: As they struggle with the sail, Skipper's hat is backwards. After a shot of the shark, his hat's on right as he tosses the sail.
Continuity mistake: As the raft starts to sink, Lovey goes into the water on the back side of the raft. When the camera is in a close up of Mr. Howell, she's sitting beside him again. Then she's neck-deep in the water in the next wide shot.
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.
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.