Fun fact about the making of Rocky IV: Sylvester Stallone suggested he and Dolph Lundgren hit each other for real.
Stallone took some body shots and felt a burning in his chest, but like any red blooded American in the mid ‘80’s pretending to fight a Russian, he ignored it, and soldiered on. Unfortunately, the giant Swed pretending to be a Russian was in fact a legit martial artist, and had done some serious damage to Stallone. Within a few hours, when the star’s blood pressure hit 200, it became apparent all was not well, and he was flown to Santa Monica where in spent between four and eight days in the ICU.