Parts of Nutcracker are impossible, for example, just after the opening of the second act. I do that part the same way as the cadenza, one hand, then the other, double speed. I suspect that Tchaikowsky expected the two harpists to sort it out between them, but nowadays, it’s usually done by one beleagered harpist. La Forza del Destino has a figure where you need five fingers to play it, but most of us leave out a bass note so that we can use the left thumb to get the bottom note of that figure. (See Bea Rose’s book.) Respighi’s got a series of impossible harmonics passages in The Pines of Rome. The Walton Violin Concerto has another very fast harmonics passage that just barely works. Britten’s War Requiem has unplayable sections…actually, this list couold go on for pages.