Casper Van Dien was already used to doing physical work and stunts for the film, including a long fistfight scene and one in which his character was subjected to a public lashing. But when Van Dien had to finish a stunt in which Rico had to jump off a tanker bug, the actor ended up cracking several ribs in the process (via Screen Rant). Van Dien apparently said that he coughed up blood after the stunt went awry. It’s not as bad as the injuries several characters suffer in the film while fighting the alien bugs, but still not fun either. Plus, y’know, it was real.
Van Dien clearly didn’t have any hard feelings over the mishap, and returned to the Starship Troopers franchise, reprising his role for its third installment, 2008’s Starship Troopers 3: Marauders. That, of course, wouldn’t have been possible if one of the other famous actors who auditioned for the role of Johnny Rico had landed the part.