This is the first acting role for children Alejandro Quintero and Matilde Manzo. They were trained during 3 weeks by casting director Leandro Arvelo and director Gustavo Sanchez.
The song chosen for the scene where Lelo (the little sister) plays the piano was Chopin - "Prelude in E Minor". That's the song Chopin wanted to be played at his funeral, this makes perfect sense in this particular scene because of what is happening.