The Starlost The Beginning (1980)

Three farmers in Cypress Corners discover that farm life is not so simple Discovering a hidden door in the earth they break through it discovering they are not on Earth but in a giant Noahs Arklike spaceship The spaceship is made up of giant domes holding the various cultures of humanity Eventually they find the bridge its crew dead and its computer complaining that the ship is offcourse heading into the path of a distant sun The three farmers take it upon themselves to travel the ship contacting the various cultures of humanity in search of somebody who can correct the course of the ship and save mankind