While the actual performances of Beethoven's piano pieces in this film were not played by Gary Oldman, the actor practiced five hours a day so that his movements would be in time with the performances of Murray Perahia, which were done off-camera.
What Beethoven says to Schindler during their first meeting (a rehearsal of the Kreutzer sonata) is taken from Tolstoy's short story "The Kreutzer Sonata".