The Beatles on Help Movie set 1965. I always wanted a mixture of all their rooms...the piano from Paul's room, the sunken bed from John's room, the grass floor from George's room, and the vending machines from Ringo's room :)
The Shining (1980) twins were played by a pair of real life twins named Lisa & Louise Burns. They doubtlessly hold the record for being actors most famous for being on screen the least amount of time. Neither made another film.