It was director Farah Khan's desire to bring Sanjay Dutt, Shah Rukh Khan, Aamir Khan, Salman Khan and Saif Ali Khan together onscreen for the first time ever. However, Aamir Khan refused to make a cameo appearance.
In the song "Dastaan-E-Om Shanti Om" you can see Shanti's ghost on a balcony behind Mike, just after he chased Sandy for the first time. The ghost of Shanti is wearing the same costume as Shanti did when she died.
Salman Khan had already finished shooting his portions for the song Deewange Deewange but when he came to know that Dharmendra would also be shooting his scenes that same day, Khan waited three hours for the opportunity to dance with him in the song.
Farah Khan was originally going to make a film called "Happy New Year." The film was to be a romantic comedy set at New Year's Eve and would star 'Shah Rukh Khan', Juhi Chawla, Raveena Tandon, Amitabh Bachchan, Manisha Koirala, Sanjay Dutt, Zayed Khan and Priyanka Chopra Jonas. However, due to the actors' scheduling conflicts, she scrapped the idea and chose another concept based on/inspired from various 1970s films
Farah Khan: The aggressive junior artist next to whom Om Prakash danced during the "Om Shanti Om" song shooting (during the credit titles at the beginning of the film).