The film seemed jinxed from the beginning of its conception.Prakash Mehra wanted to make the film with Amitabh Bachchan and Vinod Khanna in 1979. The film was titled "Ghulami". When Rajneesh heard about the film, he objected to Vinod acting in the film . At that time, the script had Vinod as a follower of a fake guru. Rajneesh felt that the film Ghulami was mocking him . But the film got shelved when Vinod decided to quit films. Prakash Mehra had decided to make the film with Kunal Goswami sometime in the 80's, but that idea also did not work. Prakash Mehra then wanted to restart the film once again in 1986, but Amitabh was concentrating on a political career. Mehra had thought of signing Vinod Khanna for the lead role with either Mithun or Sanjay Dutt in the second role. But the film once again fizzled out. Thats when Amitabh asked Prakash Mehra why they were not working together.So finally the film went on sets on December 21, 1987. Prakash Mehra finally once again restarted the film with Amitabh. Mehra approached Vinod for the secondary role, but Vinod and Vinod signed this time. But he left the film due to Prakash Mehra not agreeing to pay his price. Vinod wanted the same amount as Amitabh. Mithun Chakraborty was then signed for the role and even shot for it. He too exited the film as he realized he had a very weak role in the film. That is when Prakash Mehra signed newcomer Aditya Pancholi.
The movie was announced in 1987, but Amitabh Bachchan did not commit any dates for its shooting. During that period Amitabh attended a party in which Prakash Mehra was also present. Prakash Mehra got drunk and blasted Amitabh in front of entire film industry for not giving preference to Jadugar. Prakash Mehra said Amitabh has forgotten how he was the one that gave Amitabh Bachchan a break in Zanjeer (1973) etc. Everybody thought that after this incident Mr Mehra can forget about Jadugar. But after the party Amitabh went home and picked up his phone.He dialed Praksh Mehra no and said, "who said I'm not doing your Jadugar? Just count me in on it."
The song " Murga Hua Deewana" was a remake of the song " Baithak Gana, Parosein Apni Mugi" by Harridath Jairam ( South American born Indian artiste.). Amitabh heard the song in Holland and loved it. He then purchased the song from Harridath. In 1986 the song had another version called "Padosi Tere Murgee" was in the film Main Balwaan. The song was not in the film. Bappi Lahiri's song "Tere Kurte Ka Button Ban Ke Baby" ("Khooni Murdaa", 1990) also had the same tune as the mukhda of this song. It is possible that both songs were inspired by the same folk song.
The song " Aaye Hain Duein Dene" sampled Pet Shop Boys "Domino Dancing".
In Jaadugar,the funny character Amitabh plays in the scene with a white hat,glasses and mustache, has very funny voice. This was the scene where he speaks to Amrish Puri about his 6 wives who have gone missing. That was the same funny voice he used in the film Khud-daar, when he dressed up as a old man and tricked Praveen Babi ( before the song Angrezi Mein Kehte). He then used that same funny voice in Gereftaar during the drunk scene with Kamal Haasan. The funny character's appearance was almost the same as the Parsi character Amitabh played in a comic scene in Shahenshah.