Training or otherwise. I'll list two training related things.
Aerobic conditioning is overrated. I know what it's like. People compete in tought competitions with tough events and feel they don't have enough stamina, endurance, aerobic capacity, whatever it is. So they take it as one of their big goals to reach.
But let me tell you something. Those things will always be hard. No matter how you train, log press medley of 5 logs in 90 seconds will kill you! I think people should realise this. Some have even gone so far saying that strongman is 50/50 aerobic conditioning and strength. I think this misdirects the beginners starting in the sport.
(Direct) bicep training is underrated. I don't have much for my argument here, except that I feel like it. One thing I have to say though. I don't agree with people who say not to train the biceps to protect them from tears. By default stronger is stronger, also stronger against tears. It all boils down to knowing your own limits. If your bicep hurts, take it easy. If the tire you are about to flip frightens you, skip it. Either take responsibility for your actions or stop complaining about the hazards of the sport. But of course there are also accidents that could not have been prevented. So it's not all black and white.