While filming an action scene, Amitabh Bachchan was doing his own stunts. He had to fall onto a table and then on the ground. But when he jumped towards the table, the corner of the table hit his abdomen. He had a splenic rupture and lost a large amount of blood. He was flown out and needed urgent operation (splenectomy) and was critically ill for a while. A rumor spread that he had died from the accident. The nation (most of it anyway) mourned. Later there were mile-long queues of well-wishing fans outside the hospital where he was recuperating.
During the fighting scene where Amitabh Bachchan was injured, the moment is marked with a freeze frame, and a message is displayed in English, Hindi, and Urdu - "This is the shot in which AMITABH BACHCHAN was seriously injured".
A poster of the movie Gopichand Jasoos (1982) appears in the background of the railway platform when Iqbal has his first fighting encounter with Vicky. Gopichand Jasoos starred Raj Kapoor who is the father of 'Rishi kapoor' who plays the role of Sunny in Coolie.
Amitabh Bachchan commented on the accident saying that Ironically he had done lot of stunts in the film which were risky but nothing happened, like jumping from the railway Bogey or rolling down the steps.
The trivia item below may give away important plot points.
Manmohan Desai originally proposed a sad ending for the film. Amitabh was to die in the climax, but it was decided that after Amitabh's real-life fight with death during the shoot, the audience would not accept his death in the movie. So the climax was changed and a happy ending was shot.