MGM's contract with Disney excluded some of the best-known MGM movies.
Originally Posted by Mr_Incredible
According to The Disney Touch by Ron Grover:
MGM also protected 35 of its classic movies, including Gone with the Wind, The Wizard of Oz, the James Bond series, Rocky, and several Woody Allen movies, by requiring Disney to obtain special permission to use anything from them. By September 1986, the granting of special permissions had begun. Disney requested and got the right to use portions of The Wizard of Oz and Singin' in the Rain for audio-animatronic characters sprinkled throughout The Great Movie Ride.
Before the park even opened in 1989, Ted Turner bought the pre-1986 MGM/UA library. Warner Bros. and Turner merged in 1996. While such transactions would not have cancelled the original contract, it meant that Disney was dealing with new owners for any subsequent special permissions.