"Millennials are much smaller"
That's a direct quote from our host during the immunity challenge. Way to body-shame the X-ers, Jeff. That final race incorporates both an obstacle course and a brain-teasing puzzle. They can choose "shortcuts" along the course in exchange for a more complicated puzzle; the Gen X-ers go for the latter option, which Probst calls "a wise choice, given their bodies." Sure enough, the lithe youths finish first.
The two tribes barely interact!
Much like the real world, the millennials don't even talk to the Gen X-ers, or acknowledge their existence. Since Gen X lost the immunity challenge, they must vote out one of their own. David is already shaping up to be too much of a Chad to get the boot, so he is sticking around; instead, we say goodbye to someone named Rachel, who basically only complained about the weather and let her teammates down when it came to solving that puzzle. I don't think she did much else; maybe while I was checking Instagram. Bye, Rachel.