Gilligan's Island (1964)

Season 2: Episode 26

The radio reports that Mr. Howell has been rescued and is spending all of his money. Obviously, there is an imposter! The real Mr. Howell is frantic, and offers a reward to the person who can come up with a plan to get him back to civilization. Meanwhile, the imposter falls off a luxury liner and ends up stranded on (you guessed it!) Gilligan's Island. There the imposter conks Mr. Howell on the head with a coconut, changes clothes with him, and attempts to continue his masquerade as the millionaire.