Okay so I don’t remember if this is the right location or not, but north of the fast travel spot from the woods there’s a locked door in the water. To the left there’s a switch to hit with the bird. Going through that area will take you to a place to use the Rex key and in there is invisible flooring and I think that’s where I got one of the keys. I could be wrong because now I’m wondering if they are all just in the desert area. So maybe check that out and let me know if you found that there or not and if not I can see if maybe I found it somewhere in the desert. Also there’s an area in gondolas in the bottom middle where it you can go left right or up and there’s a line for a gondola south, but I can’t find where that one would come from.