Executive Meddling: For the American premiere at Radio City Music Hall, Disney had to shorten the movie by at least 20 minutes, to make room for a Rockettes performance. Those scenes remained missing for 25 years, until the 1996 restoration. Later, the 2014 restoration deleted them again.
The Other Marty: The original audio for the deleted scenes apparently no longer exists, requiring Disney to have the dialogue re-dubbed. Angela Lansbury and Roddy McDowall re-recorded their own lines, but characters whose original actors had either passed away or become too old received new VAs for these parts.
Reality Subtext: Supposedly, "The Age of Not Believing" is "really" about the Disney Company's struggle to continue after the death of Walt Disney.