Watch the special expanded series finale online now.
The cast is all jitters and nerves: they're going to perform with the famous Rebecca Duvall! Fearlessly approaching the piano, Rebecca dives right into the music. In shocked horror, Eileen and the cast quickly realize Rebecca can't sing. Derek proposes they bring Ivy in for vocal support. Now that the musical has a celebrity tacked onto the cast, Karen is pushed back into the chorus.