The film was jointly written by Hirani and Abhijat Joshi.
Sanjay Dutt’s wife Manyata Dutt had suggested the idea of the biopic to Rajkumar Hirani.
Hirani, who had directed Sanjay in three films, was disinterested in the world of guns and drugs. After several conversations with Sanjay, he envisioned the biopic as a father-son story.
Hirani had first approached Aamir Khan for the role of Sanjay Dutt’s father Sunil Dutt.
Ranbir Kapoor was Hirani's first choice to play Dutt's character.
Amitabh Bachchan and Anupam Kher were also briefly attached to essay Sunil Dutt. The role finally went to Paresh Rawal.
Ranbir Kapoor requested and was given a month's break between every phase to complete his transformation into Dutt.
Vicky Kaushal’s character Kamli was an amalgamation of Sanjay Dutt’s best friend Paresh Ghelani and other friends.
The replica of Sanjay Dutt's childhood home took 25 days to create.
Boman Irani appears as the father of Rubi (Sonam Kapoor). He is also glimpsed in the archival footage of Munna Bhai MBBS
Boman Irani has appeared in every Raju Hirani film so far
Sanjay Dutt paid a surprise visit on set. He also appears in the end-credit song Baba Bolta Hai
The film was tentatively titled Aisa Hi Hoon and Dutt. Finally, the title Sanju was chosen based on what Sanjay Dutt’s mother would call him.
Manisha Koirala played Sanjay Dutt’s mother Nargis Dutt. Manisha and Sanjay were paired on films like Yalgar, Sanam and Kartoos.
Ranbir Kapoor and Sonam Kapoor reunited in Sanju 11 years after Saawariya.
Dia Mirza made her comeback after six years as Manyata Dutt
Sanju’s poster was released on the 37th anniversary of Sanjay Dutt’s debut film Rocky (1981).
The CBFC asked the makers to remove the overflowing toilet scene for ‘aesthetic’ reasons. A complaint was also filed by activist Prithvi Mhaske for portraying prison cells negatively.
Sanju became the highest grossing domestic release (nett) of 2018
Sanju lifted Ranbir Kapoor out of a career slump after Roy, Bombay Velvet and Jagga Jasoos
The film was criticized for whitewashing Sanjay Dutt’s past and omitting his underworld and political connections.
Ranbir Kapoor had trained with stand-up comic Dr. Sanket Bhosale to mimic Sanjay Dutt
Sanjay Dutt and Ranbir Kapoor are starring together in Karan Malhotra’s Shamshera.
Sanju emerged as the highest-grossing Bollywood film of 2018, the second highest-earning Hindi film in India of all time, and one of the highest-grossing Indian films.
Post the release of the film, both Hirani and Joshi reasoned that Dutt has not been 'whitewashed' in the film, despite the general consensus in the media.
Hairstylist Aalim Hakim revealed that it took '22 days to finalise Ranbir's different avatars' as it was a 'challenge' to create the 'receding hairline for Ranbir and give him a broad forehead'
At the wrap party, the cast and crew were seen wearing personalised T-shirts with the hashtag '#duttstheway' in order to promote the film.
A replica of Dutt's childhood home which he lived in with his parents took 25 days to complete, as Hirani wanted to portray's Dutt's life right from childhood to the present day.
The film's soundtrack was composed by AR Rahman, Rohan-Rohan, and Vikram Montrose.
The background score was composed by Sanjay Wandrekar and Atul Raninga. Vidhu Vinod Chopra,
