In a deviation from Bollywood traditions, the OST has been composed entirely by independent music artists. Early in 2014, Banerjee and his production team set out to find artists whose music would fit into the story of the film. After shortlisting about 200 songs from non-Bollywood artists across the country, the team began whittling the list down to a handful of songs and artists.
Aamir Khan was offered the villain's role in the film but declined it to take a role in Dhoom 3 (2013), another Yash Raj Films production.
Sushant Singh Rajput had to apply oil for his hair for every shot as the film is set in 1940s.
At the 30-minute mark, the as-yet-unnamed Angury Devi (Swastika Mukherjee's character) asks Byomkesh if he has never seen her. Byomkesh is seen walking past an advertisement bearing a likeness of Anguri Devi as part of an advertisement for a "beauty soap" behind a bus around the 14-minute mark, as the opening credits are being shown.
Rani Mukerji was the first choice for the role of Anguri Devi. The actress however balked at the character's risqué scenes and so Swastika Mukherjee (no relation) was cast instead.