In one of the sequences for the climax, which was a car chase, John was required to dodge cars coming towards him from all directions. However, he lost control of the situation as his judgment went wrong while driving.
Hence, due to a miscalculation, he applied the brakes suddenly, which resulted in a back sprain. He was in severe pain till the doctor came.
Medical help was immediately provided to him on the sets as he was unable to sit after the mishap. However, John was back on his feet after some rest, a couple of physiotherapy sessions, and a few painkillers.
Nonetheless, he is advised to be a lot more careful with his back for a couple of weeks.