Visible crew/equipment: When Gilligan is packing, Skipper sneezes and blows out the candle. The third time, Gilligan blocks the candle, and if you watch the right side of the screen, you see the tip of somebody's nose pop into the scene as he blows out the candle.
Revealing mistake: When Skipper is blindfolded, as he rears back getting ready to sneeze, watch his right shoulder. You can see the line that pulls the blind off when he sneezes.
Revealing mistake: When Skipper is sneezing after Gilligan showered, he turns towards the wardrobe. As he sneezes, in a "blink and you miss it" moment, the line pulling up the bottom of the green cloth is momentarily visible, pulling from the upper right corner of the screen.
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
Plot hole: The scientist yells for Igor to capture the escaping Castaways, to which Igor responds "capture them yourself" in Ginger's voice. The scientist appears surprised to find out Igor is not Igor, but how can this be? He had to be the one to pull the lever to switch everyone's personalities and bodies around, so he should have already known.
The Friendly Physician - S2-E29
Factual error: When the castaways are coming back to the island at the end, you can see some of the Los Angeles buildings in the background in the high camera angle.
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.
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'.
The Friendly Physician - S2-E29
Continuity mistake: After Skipper admonishes Gilligan for his suggestion, Balinkoff says "No, no", and starts to gesture with his right hand. After the angle change, he starts to gesture again.
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.