This was meant to be Kajol's comeback venture, alongside her husband. However, she couldn't accept due to other commitments.
Karan Johar claims he was inspired to do a thriller instead of his usual family film by Aditya Chopra, who had broken Yash Raj Films out of their romantic film mold by doing the action film Dhoom (2004). He paid tribute to Chopra by casting that film's stars, John Abraham and Esha Deol.
The protagonist's name, Kali Pratap Singh, is a reference to Veer-Zaara (2004), where Shahrukh Khan and Karan Johar had respectively acted and designed the costumes.
Saif Ali Khan was offered the role of Dev Malohtra, but he declined.
Nana Patekar was originally offered the role of Kali Pratap Singh. Along with him were Saif Ali Khan and 'Shahid Kapoor' who were had a mixed feeling when offered.
'Vivek Oberoi' was originally offered the role of Kali Pratap Singh, but couldn't do it because it wouldn't fit his schedule. Later on, he accepted to role of Dev.
Priyanka Chopra was offered the role of Riya, but she couldn't, due to other commitments.