And, correct me if I'm wrong, but doesn't he also get knocked into the fire with the ballerina and they get stuck together? Or am I thinking of another story . . .
Disney sketches drawings that go well with the music being composed. Are we, then, to believe that there is an error with the whole movie because of the sketch for Pomp and Circumstance? Donald Duck freed the animals from the flood, not Noah! I don't think we need to be nit-picky.
Remember, though, that Donald Duck plays the part of Noah; the tin soldier does not play the part of the jack-in-the-box. Even so, this is still not a slip-up. It was quite intentional. I have yet to see a Disney take on a previously written story in which the story was not changed.
On the DVD commentary, the directors and the guy that composed the orchestra do say that the original ending to Shostakovich's Piano Concerto No. 2, or better known as the Tin Soldier sequence, was totally different from what it ended up with. Originally they had it as the Tin Soldier falling into the fire with the jack in the box, and melting into the shape of a heart, but they decided that the ending of the music score was lively and not dramatic, so they changed it to a happy ending.
Umm, I don't think Donald Duck is Noah because toward the beginning of that story, you see an old man with a long beard telling Donald to get the animals onto the ark. I assume that Donald was playing one of Noah's sons, but he's obviously not Noah.