Sylvester Stallone decided that for the shooting of the fight in "Rocky IV" (1985), he and Dolph Lundgren should hit one another for real, so as to increase the intensity of the scene. After doing three takes of Rocky taking shots to ribs, Stallone felt a burning in his chest, but ignored it. Later that night, he had difficulty breathing and was taken to a nearby emergency room. It was discovered that his blood pressure was over 200, and he had to be flown on a low-altitude flight from Canada to St. John's Hospital in Santa Monica, where he remained in intensive care for four days. What had happened was that Lungren had punched him so hard in the chest, Stallone's heart had slammed up against his breastbone and began to swell, cutting off the blood supply and restricting the oxygen flow throughout the body.
Stallone's insurance company thought he was faking it, saying that his injuries looked more "from head-on collisions when the steering wheels hit you in the chest." Stallone replied, "Have you seen Dolph Lundgren? That's a truck! That's a steering wheel! That's a head-on collision!" His insurance company honored the claim soon after that.
Over 8,000 people auditioned for the part of Ivan Drago. Lundgren was first turned down by the casting directors for being too tall but later on, he got the chance to send photos and meet Stallone who told him he had a good chance to get the part, but advised him to gain twenty pounds of muscle. In total, it took Lundgren several months to win the part.
During filming, Lundgren and Carl Weathers really did not get along and got into an altercation. Lundgren threw Weathers into a corner of the boxing ring. After that, Weathers shouted profanities at Lundgren while leaving the ring and announced that he was calling his agent and quitting the movie.
Only after Stallone forced the two actors to reconcile did the movie continue.
This event caused a four-day work stoppage while Weathers was talked back into the part and Lundgren agreed to tone down his aggressiveness.
Happy Birthday, Dolph Lundgren!