The Castaways on Gilligan's Island (movie, 1979)

Stuck on the same island as before, the castaways find an abandoned World War II bomber that the Professor is able to repair and fly. However, in the attempt to fly to Hawaii, Gilligan falls out and has to parachute down to the island. Against their better judgment, the gang decides to return the island to get him. In a stroke of luck, that saves their lives as an engine collapses upon landing instead of in midair. Even better, a U.S. Navy captain appears saying that their plane was detected on radar long enough for them to follow it to the island. A year later, the island is now a tropical resort spot fully linked to Civilization, and the castaways work as the staff as they work to entertain the various guests they receive.