The police station scene was meant for just one minute duration, but the actors in the scene stretched it to 14.5 minutes while improvising.
Anurag Kashyap personally requested the parents of child actor Anshikaa Shrivastava who played Kali Vasrsheney, not to allow her to see the film because of its dark theme.
The actors, supposedly, weren't given a hard script. They were given dialogues & a scene was described to them and were made to act accordingly, on spot.
The lead actor Rahul Bhat used to stay in the same apartment building that Anurag Kashyap stayed in, in his struggling days.
This movie was made and was ready for release in 2013 itself but since the director Anurag Kashyap wanted the statutory warning regarding Smoking to be removed he did not release the film till Dec 2014. Fighting a lone battle with authorities, he finally had to give in keeping in mind the monetary aspect of the producers.