Executive Meddling: ABC wanted more westerns from Disney during the later 50s, which brought out a lot of "Frontierland" mini-series like Elfego Baca and The Swamp Fox. This was one of the reasons Walt fled to NBC, the other being that NBC had the technology to broadcast in color, while ABC could only broadcast in black and white.
While the show was doing good on CBS, Disney didn't let the show go on after the 1982-83 season so there wouldn't be any competition with the new Disney Channel.
"The Mickey Mouse Anniversary Show" is narrated by Disney regular Dean Jones, of The Love Bug fame.
Keep Circulating the Tapes: The total number of episodes available on DVD seems pretty small when considering how many seasons this show has. Worse, while Disney Blu-Ray Discs contain excerpts of varying lengths, only two full episodes have become available to own on Blu-Ray: "The Peter Tchaikovsky Story", as a bonus feature on the Sleeping Beauty Platinum Edition (but not the more recent Diamond Edition), and "The Best Doggone Dog in the World", as a bonus feature on the 101 Dalmatians Diamond Edition.
Network to the Rescue: After the show was dropped by NBC due to low ratings, CBS was quick to pick it up in 1981.