Thanks to the Free Music Archive for the music used in the film. You can listen to or download all five Anonymous Choir songs here:
Antonio Lotti's Missa
Giovanni Croce's Cantato Domino
Tomás Luis de Victoria's Amicus Meus
Tomás Luis de Victoria's Caligaverunt Oculi Mei
Tomás Luis de Victoria's Unus Ex Discipulis Meis