Our sources reveal, "On one occasion, when the film was being shot in Delhi, Bachchan had to report for his makeup at 2 o'clock in the morning for a 6 o'clock shift.
What's worth noting is that the superstar landed in Delhi the previous evening and had to attend a dinner party at close friend Amar Singh's residence. He returned to his hotel room well past midnight and got barely an hour to sleep as he had to be with the makeup artist and the prosthetic people at 2 a.m."
Our source further adds, "Since Amitabh plays a 13-year-old in the film, he used to spend most of his time on the sets with kids rather than with other unit members.
While dubbing his dialogues, he used to wear his dentures (with broken teeth) which he has worn in the film so that he could get the correct childish accent, probably with a lisp."