When you fold up the rear seats, (the main rear seats, not the far rear jump seats) is there supposed to be something that holds/locks them in their retracted position? I looked for a strap or something, but didn't see anything. Do they just stay in place without any restraint? Seems like they would fall back down if you went up a steep slope or bounced around a bit.

Do they stay folded up without the need for any restraint when traveling over rough terrain?

 

Nope, just fold them up.
Your gear will hold them in place.

 

Yeah they make a restraint, it's called a 2 by 4.