The Doctor plays the opening line from Bach's "Toccata in D-minor", but hits the wrong notes on the keyboard. The notes are supposed to be A, G, A, G, F, E, D, C-sharp, D; he plays C-sharp, C, C-sharp, C, B, A, G, F-sharp, G. Even if he was trying to play in a different key, the notes would not match; the closest key to the notes being played would be G-minor, which would sequence D, C, D, C, B-flat, A, G, F-sharp, G (matching 5 of the 9 notes).