In November 2014, the team behind Disney’s Zootopia had a very bad day. After years of development and production, they realized a huge aspect of their movie didn’t work. There were two main characters, one primary and one secondary— and they had to be flipped for the film to make sense. ...
But here's the rub ...
This is the same story, all the way back to the beginning, of most every animated feature ever made.
Take, for example, Ward Kimball's recollections on a long-ago Disney feature:
... Walt realized [Pinocchio] wasn't working. And he threw it all out and started over. ... I tend to forget the problems we had, and that's the tendency of everybody, but Pinocchio was no soft touch. In fact, I thought it was harder for everybody than Snow White. We finished Snow White and we said, "Ha. We know how to do features!" And everybody went into Pinocchio with this great load of confidence. Boy, six months later we found out, and Walt found that, that what you learn in one picture doesn't necessarily work on the next picture.
Then Walt brought in the cricket, added that little personality. The story needed something to bounce Pinocchio's problems off of. How do you bring a marionette to life? How does he know the facts of life unless he has some tutor? ... See, the cricket has educated Pinocchio and you get a kick out of Pinocchio's mistakes and his naïveté, his unworldly approach ...
Sound familiar at all?
And of course, they threw sequences out on Snow White and the Seven Dwarfs. ... Recut and rejiggered The Rescuers. ... Performed major surgery on Aladdin, throwing Aladdin's mother overboard, getting rid of songs, etc., etc.
Toy Story got redone multiple times. Shrek went through the death of its original lead actor, causing big changes in the lead character.
Remember this interplay? Neither do I.
With Shrek I DWA story crew put gags in, took gags out, and worked forever to get the tone they were looking for. And even when they were done they weren't sure they had a hit. (Happily, they did.)
And then there is Tangled, which went through a dozen years of story work before coming out and giving the Mouse a major hit. It seemed like every twelve to eighteen months there was a new version of the picture. And like Zootopia, a DreamWorks feature titled How to Train Your Dragon had a big redo a year before it came out.
So. Changing a picture in mid flight? It happens. In fact it happens all the freaking time, all the way back to the 1930s.