Film was a remake of Dragonfly 2002 .Anurag Basu explained that the film is also inspired from real life incident happened in Mumbai when a man traveling in local train heard his late mother's voice telling him to get down from the train.As soon as the man got down the train met with an accident on the next station.
The song "O Saathiya", sung by Alka Yagnik and Udit Narayan, was originally recorded for the 1998 film Zakhm and song is written by Anand Bakshi, but was included in this film.One of the final films of Lyricist Anand Bakshi released after his death.
John Abrahams voice was dubbed in the film.
Katrina Kaif was director's first choice for the leading role but on john wanted the director to take someone who speaks the language well, so on john's request the director changed the leading lady.
The film was originally titled Nastik.