Kay Kay Menon was the first choice for the lead role (K), but he declined suggesting Kashyap to cast an actor having stardom. Anurag then offered SRK the role, who ultimately declined as he felt that the movie promotes 'anti-smoking' feelings. John Abraham was the only star-actor to love the script, and agree to do it.
John Abraham who quit smoking, had to smoke 99 cigarettes a day to get into the character which resulted in his lungs getting affected.
Anurag Kashyap's then-assistant Vikrmaditya Mothwani (director of Udaan) appears in a shot where he shows us the middle finger, smoking a cigar in John Abraham's office right after John passes an order to ban the smoking in his office. Currently Vikramaditya is producing films along with Anurag through their co-production called "phantom".
The film Ayesha Takia watching in one scene is 'Schindler's List',the perticular scene has subtle similarities with the end of 'No Smoking'