The recipients of Khan's generous gifts reportedly include Arjun Rampal, who played the title role, director Anubhav Sinha and the south Indian superstar Rajinikanth, who made a cameo appearance in the film.
A source told the Mumbai Mirror: "Shah Rukh has decided to gift one of the five BMWs to Anubhav Sinha. One car will go to Arjun Rampal. Since Rajinikanth flew down to Mumbai to shoot specially for his cameo in the film, he'll get one car.
"There are two more people on the gift list. However, no one is aware of SRK's plans. The cars have already been booked with a local dealer. Once the delivery comes through, the gifts will be on their way."
Talking about the actor's previous gifts, the source said: "Shah Rukh has always been a generous friend. Earlier, he had gifted Farah Khan a Hyundai Terracan during the making of Main Hoon Na. He even gifted her a Mercedes during Om Shanti Om."
Ra.One is a box office success, reportedly grossing over Rs 100 crore (£12,438, 971) in India.
Speaking to Digital Spy at its London premiere, Khan described the film as "something quite special".