When I saw this, I at first thought the ending was reminiscent of the ending of "Who Framed Roger Rabbit", which, as you know, ends with the whole crowd of Toons (Disney and non-Disney alike) learning that they are now the new owners of Toontown and all singing, as one, "Smile, Darn Ya, Smile". However, I had a rethink and thought it wasn't the best comparison. I thought, for sheer emotion from a big crowd singing a rousing emotional song, a more apt comparison would have to be the finale of "The Muppet Movie", which ends with not just Kermit's crew, but almost every single Muppet in existence (even those from "Sesame Street") all singing "Rainbow Connection". It even ends with the camera showing a closeup of one character and then pulling away to reveal the gigantic crowd as they all sing. Watch:
I also drew comparisons from two other things. The first was from an episode of the old Disney anthology series called "This Is Your Life, Donald Duck", which ends with a whole crowd of Disney characters, at host Jiminy Cricket's behest, parading out onto the stage to pay tribute to Donald while singing "Quack Quack Quack Donald Duck" (which originated from another anthology episode called "A Day In the Life of Donald Duck"):
The second was this one ad for Eastern Airlines, which was one of the original sponsors of Walt Disney World in its early days, going so far as to sponsor an old attraction called "If You Had Wings" (where the Buzz Lightyear ride stands today). This ad apparently came out around the same time as "Robin Hood", since he and Little John are clearly spotted in the big crowd of Disney characters accompanying a generic family on a flight (via Eastern, of course) to WDW: