I got onto and explored the first platform the dragon lands on, behind and under it, went around to the burning scaffolding where the ladder is and nothing. I also explored the backside of the third platform area where you kill the dragon and nothing. Haven't tried to get on top of the second platform yet though. It's great that the game lets you explore so much! I've always been that person who goes to the edge of a map just to see if anything is there.
*Take your horse to the stair step rocks on the entrance side of the first platform and you can jump to the platform. From there to get to the scaffolding and behind in the grassy knoll, use your horse and jump off the stacked stones to the stair step rocks on the entrance side, once you get up to the top, you can walk around the back into the area with the scaffolding. Your party shows up on both the platform and on the grassy areas and scaffolding, so you can save and explore at leisure.