It's Day 16, and time for the Immunity Challenge. Once both tribes arrive and assemble, Probst explains the details. They will have to assemble a wheelbarrow, fill it with coconuts, and maneuver it through an obstacle course, dumping the coconuts in a trough, and then go back for a second load of coconuts. Then the second half of the tribe has to take the wheelbarrow apart, and use the pieces to create a slingshot, which they will use to shoot coconuts at targets. First tribe to knock down all of the targets wins immunity and reward. Edna is useless and will sit out for Upolu.
In the first half, Upolu has Brandon, Sophie, and Rick working the wheelbarrow, while Ozzy, Dawn, and Cochran do the same for Savaii. They get their wheelbarrows assembled at about the same time. Brandon and Rick fly through the course together with the wheelbarrow, but Ozzy and Dawn struggle. I think the problem is that Ozzy is trying to do the whole thing himself instead of trying to work in concert with Dawn. So Upolu gets all their coconuts dumped and their slingshot assembled, while Savaii is still trying to get their second load of coconuts. When Savaii tries to dump their second load of coconuts, Ozzy tries to do the whole thing himself, which doesn't work, and Cochran "tries" to "help" but seriously isn't doing anything at all. Useless.
Finally both tribes are slinging coconuts: Albert, Coach, and Mikayla for Upolu and Jim, Keith, and Whitney for Savaii. The first few shots for both tribes are duds, because you have to figure out how far back to pull the slingshot and what trajectory to aim it at, but they get it pretty quickly. Albert gets the first target down for Upolu. Mikayla is doing a weird one-handed technique and she's not taking down any targets, but she's coming as close as anyone else. Coach immediately decides that Mikayla isn't contributing, so he tries to get her to "rest for a while" but she's like, "I'm not tired." After her next attempt, Coach asks if she wants to just sit out, and she says no. Look, all he had to say was, "Albert is the only one hitting targets. Why don't we BOTH let him do this?" Because Coach hasn't hit any targets and he's not coming any closer than Mikayla is. If I were Mikayla, I wouldn't want to sit out either. That's just giving your tribe a reason to vote you out, and she knows she's on the chopping block.