I am wondering what those blue tiles, cards? are next to Mike on the bench...did they come in tree mail? And, he is holding something that has a cord around it on his lap? I can't help but think these might be before the challenge?

I tried blowing up the photo and it still's hard to tell what's in Mike's lap since it's the same color as his shorts, but it kinda looks like a whistle or a spray nozzle or something metal. It also looks like Mike's arm is resting on a litle barrel or something made of wood. Not sure if that was around already or not? Or is it just his canteen or something to old water?

Re the tiles, metal-thing, etc: Could this be what comes with the tree mail regarding the next challenge? If so, can we put the 3 items together and maybe come up with a potential challenge? Another option is that maybe this is what comes with the tree mail to announce the next RI duel. I suppose the tiles could signify the dominoes? Or maybe this is related to how they pick who gets to go this time, vs. the rock?