Mentzer was mad because Arnold entered the contest at the very last minute. The rules stated that all competitors must register 3 weeks prior to the contest - this rule was obviously waived for Arnold. You see Conan was supposed to start filming in 1981, however that date was brought forward unexpectedly. The first scenes were to be shot in August 1980. In addition, Universal, the films distributor was going to use thise footage as a promo along with it's Christmas release of Flash Gordon. All of a sudden, Arnold had to get big, and fast. The best way to get big - and to get attention doing so - was to attempt the unthinkable: to make a comeback! You see Arnold was scheduled to arrive in Sydney as a TV Commentator only - so you can imagine everyone's surpise when he registered to compete at the very last minute. Mentzer was pissed. Reg Park was also put in a precarious position as he was one of the judges and of course him and Arnold were very close. Paul Graham was the promoter of that event and him and Arnold were also very close - he is the big guy who pulls Arnold in and hugs him in the very beginning of the movie Pumping Iron. The argument between Arnold and Mike Mentzer was over the fact that Boyer Coe was instrumental in getting the IFBB rules changed for the 1980 Olympia so that instead of a winner being chosen from the best of two weight classes he would emerge from six all-comer finalists. Arnold was the only one who objected to this. Arnold wanted only two weight classes, that way there is only one man to beat. Mentzer got pissed and told Arnold that he was acting like a baby and Arnold said to Mike, " If your belly wasn't as big as your mouth, then maybe you would have a chance at this event". Mike then jumped up and got in Arnold's face and Arnold just sat cooly and laughed it off...Classic example of mental psyche-out which Arnold was famous for since it almost always worked. Needless to say, Mentzer was not a threat to Arnold's throne as Mike ended up third, behind Chris Dickerson. If anyone had a chance to beat Arnold it was Chris and not Mike.