Music Land (the film) has not been released in any form since 1953, and it was removed from the Disney Animated Canon entirely in 1985.
This film was the last Disney film distributed by RKO pictures, who had distributed all of Disney's films up to this point. Disney was worried about Howard Hughes' leadership of RKO, and wanted to sever their ties with the studio as soon as they could. Their solution was to quickly edit together and release a package film titled Music Land (no relation to the 1935 short of the same name), which was comprised of shorts from other package films Make Mine Music (1946) and Melody Time (1948). Though the shorts were the same, the film included a new intro and ending, as well as new transitions between the shorts. This was technically enough to classify the film as a new movie entirely, and it allowed Disney to complete their contract with RKO.