Drew's body
I'm not sure I understand why they left Drew? At first, after they found him, you see them with him tied to the side of the canoe. That led me to think they were bringing him with to the end. I guess maybe that wasn't practical- all 4 of them getting down river with just the 1 canoe. Okay.
What I don't get is, why did they want to hide his body. They did have those rocks tied to him, right? Idk why they wouldn't want him found. Was it that he had a gunshot wound? That might make sense.