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.
Other mistake: All of their sheets were the same type. The sheet that the "Ghost" supposedly took from them was more silken, not the regular knit.
Other mistake: Mary Ann comes up to the Skipper while he's learning to juggle. If you look closely, the coconut bounces on the ground a couple of inches from his left foot. When Gilligan approaches, the coconut bounces off the bottom shelf. And in both times, the Skipper reacted in pain.
Gilligan's Living Doll - S2-E21
Other mistake: When the Howells give their suggestions, if you look at the dark rectangle, you can see the word REJECT before it lights up. Likewise, when Ginger talks to it, you see TILT before it lights up.
Other mistake: When Mrs. Howell looks at the lion in the mirror, the image is not reversed as it should be when the camera looks directly at the lion.
Other mistake: In the opening scene, and later, the camera shows the Howells' hut, but the scene is in Skipper and Gilligan's hut.
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'.
Other mistake: When Gilligan and the ape are staring at each other, with the idea that the ape will stay hypnotized and ignore everything else, look closely at the ape's eyes. The actor in the suit glances twice and the Skipper and Professor as they pass.
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.