The Howell hut image is used several times throughout the episode. However, it is used to show the hut where Gilligan and the Skipper live. The Howell hut has a double door entrance, while the other hut has one door and a window which show the difference.
Gilligan says the allergy is caused by Papaya nut oil. Papaya have seeds, not nuts.
When Gilligan is packing and the Skipper is snuffing the candle with his sneezing, the crew member who blows out the candle is visible on the right of the screen during the sneeze when Gilligan holds up the board in front of the Skipper.
Professor uses huge, bulky, hand-made syringes and needles to administer the shots. But later, in Slave Girl (1967), he has a perfectly good glass syringe and its sharp needle.
The Professor performs a scientific miracle by developing a vaccine to the "Gilligan Allergy", an allergy that never existed in the first place.