The house where Bobby lives with her family was made up on the 1st floor of old haveli(mansion) in Kachiguda in Hyderabad. When it was found it was just an empty, dirty shell. Fake walls were created, windows, doors were added, entire place was painted and aged, front verandah was designed set up from scratch.
The hotel 'Avasa' shown in the film where Bobby goes with Tasawur to check on Kiran Kumar's character was actually the hotel where the cast and the crew of the film were staying. The crew was put up there for the entire duration of the film's shoot in Hyderabad.
There 40 copies of 'Khan's diary' that were made for the film's production. Nobody thought that this so necessary but it so happened that last shot with 'Khan's diary' was actually shot with the actual last diary. All 40 were used in the production of the film.
Vidya Balan had to try out 122 different disguises in order to short list it to 12 looks that could be used in the film.