This film marks music composer A.R. Rahman's debut as a writer and producer.
For the Tamil version of the film, A.R. Rahman's nephew and daughter, music composer G. V. Prakash Kumar and Khatija Rahman, dubbed for Ehan Bhat and Edilsy Vargas, respectively.
Since his role required musical expertise, Ehan Bhat underwent piano training at A.R. Rahman's musical institute, KM Music Conservatory, in Chennai for more than year. He was also sent to Los Angeles for training from acting and success coach, Bernard Hiller.
The voice expressing Sophie's thoughts in the Hindi version of 99 Songs was that of singer Shashaa Tirupati.
The voice over during the title credits, at the beginning of the film, was done by singer Udit Narayan.