Every time a new Pixar or Disney Animation movie is in production I start to hear scuttlebutt along the lines of "This is the worst one they've done. It's almost unreleasable." This usually happens about a year, year and a half out from release. It happens almost every time. And it happens because people outside the process of creating these movies don't understand the process of creating these movies. They get overhauled in profound ways as they move towards final animation; entire storylines get changed, characters gets dumped, the thematic focus shifts. I was just at Disney Animation for a Big Hero 6 press event and when I'm finally allowed to write about it I'm going to write all about how that film went through a half dozen iterations before they ended up with a movie they liked.
Now it's happening on the latest Pixar film, The Good Dinosaur. John Lithgow is providing a voice for the film, told Collider he's going in to record again:
“I recorded the entire role in Good Dinosaur. They have now dismantled it and completely reimagined it, and it is a fantastic new story," Lithgow told Collider. "So I’m gonna record again on it within the next month. Don’t worry. It’s coming and it’s gonna be better than I ever imagined.”
One caveat: this happened on Brave in a big way and I think it ended up hurting the film, which felt like a mishmash. And I don't know how they do it at Pixar exactly, but at Disney Animation they don't like bringing in the voice talent until they've cracked the film - that way they don't have to tell an expensive and famous actor that their role has evaporated between test screenings. That Lithgow's part is being complete overhauled after he recorded it might be unusual.
But animation is done so differently from live action that to worry because they're redoing the movie at this late stage is a waste - these guys work in a very unique way, and this tends to be part of the process.