Im not sure if this is true or not, but if it is, it wouldnt be the first time that Stallone went to the hospital during a shoot. He suffered some internal damage after Rocky IV after intially insisting on shooting some footage of taking real shots from him and Lundgren, also he really messed himself up during the shooting of First Blood. It was during the scene where he had to jump off the cliff. Apparantly they wanted to use a stunt double, but he insisted on doing it himself, and suffered some serious injuries as a result.