Voodoo is not practiced in the Pacific region, but in the Caribbean.
When the Professor is supposed to be frozen stiff by a voodoo curse, he blinks several times.
When the Professor becomes motionless, he was in mid-sentence, looking off to his left. By the time the curse is cancelled, he was shown facing straight ahead. In addition, he had been in mid-conversation with the Skipper and Gilligan when he became "frozen". He fails to notice that the Howells are now present when he snaps out of it.
How could the Witch Doctor have Gilligan's rabbit foot when he put in the Robot from "Gilligan's Living Doll (1966)"?