Hrithik Roshan was signed for the role of Lakshman, and even shot for a day. After the success of Kaho Naa... Pyaar Hai (2000), Farah Khan did not want an actor so popular.
Aishwarya Rai was offered the role of Chandni but due to problems with Shahrukh Khan, she was signed off.
Amisha Patel was considered for the role of Sanjana.
Farah Khan wanted to have re-created Rahul Dev Burman music in the movie, but she chose not to, because the movie Dil Vil Pyar Vyar (2002) had done the exact same thing. She then told music director Anu Malik to make the music R.D. Burman style.
The film is a takeoff on the Ramayana, as the names show: Ram, Lucky (Lakshman) and Raghavan (Ravana). Also, as a reference, in the movie, Lucky (Lakshman, played by Zayed Khan) mentions that the house would feel like a Mahabarat if he kept his name as Lakshman. Then his brother and mother correct him by saying Ramayan.
The carriage Shahrukh Khan is riding when chasing the assassins has the name Dhanno written on it. This is a reference to Sholay (1975), where Hema Malini's horse is named Dhanno.
Nana Patekar was wanted to play Raghavan by Farah Khan but she was scared to approach him.
Throughout the movie, director Farah Khan used references from movies she enjoyed.
The title "Main Hoon Na" is a very popular dialogue used by Shahrukh Khan in most movies.
Originally this was supposed to be Zayed Khan's and Amrita Rao's first film but because of Shahrukh Khan's back injury this film got delayed.
Kamal Hassan was offered the role of Raghavan, but rejected the part saying he didn't wish to play an unpatriotic character.
Tabu makes an uncredited appearance in the movie. She can be seen when Shahrukh Khan is doing dance practice for the prom night.
Rani Mukherjee was supposed to have a guest appearance in a song, but it wasn't possible. That's why there are two pictures of her when Satish Shah is flirting with the lady on the phone.
The first stunt Shahrukh Khan does while walking on the wall was a secret from director Farah Khan. She didn't want him to do that stunt due to his back injury. She even threatened to tell his wife, Gauri Khan.
Farah Khan and Shahrukh Khan had started planning for this movie in 2000. Filming had started in 2001, but Shahrukh Khan's back injury and other commitments came in the way.
Sushmita Sen got the role of Chandini while working with Farah Khan in the song "Mehboob Mere" from Fiza (2000).
Farah Khan had the backup dancers appear as college students as well, instead of getting 100 backup dancers and another 100 college students. She said that there is no point seeing characters dance and different characters for support.
Shahrukh Khan hated his dance steps to Tumse Milke, but Farah Khan eventually convinced him to complete the steps.
Shahrukh Khan originally did not like the title of the movie believing it sounded incomplete. It was not until he heard the title song, when he believed the title was perfect.