Mr. Cranston asks Denise to be the accompanist for the school's upcoming production of "Chicago". In the year 2009, this would not be possible since the licensing company which handles the theatrical rights for "Chicago" was restricting the show from being produced (even by amateur groups and schools) anywhere in the greater New York area while there was an open-ended Broadway production still running.
When Marco is playing the piano at his parent's restaurant, the song he is playing is filled with sustained chords and legato melodies; which would require the foot pedal to be used quite often in order to achieve the sound that is heard. However, when the camera pans back to show underneath the piano, the pedal is not moving.