Gilligan's Island - Season 3 - Eps 24: The Second Ginger Grant
Mary Ann falls backwards while watching Ginger perform on stage, and, when she awakens, she thinks that she is Ginger. Meanwhile, Gilligan accidentally watches as the Professor attempts to hypnotize Mary Ann, and thus he begins to think that he is Mary Ann.
About Gilligan's Island

Title: Gilligan's Island
First Air Date: 1964-09-26
Last Air Date: 1967-04-17
Status: Ended
Rating: 7.431/10 (from 238 votes)
Language: EN
Seasons: 4
Total Episodes: 98
Network: CBS
Genres: Comedy, Family
Production Companies: United Artists Television, CBS, Gladysya Productions
Synopsis
The slapstick adventures of hapless Gilligan, long-suffering Skipper and their gang of mismatched castaways, all stranded on an uncharted desert isle after their tiny ship hit stormy weather.
Cast

Bob Denver
Gilligan

Alan Hale Jr.
Jonas "The Skipper" Grumby

Jim Backus
Thurston Howell, III

Natalie Schafer
Eunice "Lovey" Wentworth Howell

Tina Louise
Ginger Grant

Dawn Wells
Mary Ann Summers

Russell Johnson
Roy "The Professor" Hinkley