The occasion for today's post is that I just discovered that here is a zip line in Novaha Assembly Hall. It's not just a decoration, either, as you can hop on and get carried most of the way across the zone. It even plays a cut scene in which you crash through a couple of walls.
And most players probably run right by it without realizing it is even there. I did the first six (!) times I cleared the zone, and just noticed it when going through on yet another character. It was probably there all along.
You don't have to use the zip line. The game won't point it out to you, and no quest will take you to it. It's actually not in a terribly useful spot, as it takes you back to the start of the zone, and the one time you want to do that, a quest completion teleport will do it for you. But it's there for you to find.
The game has quite a few things like this. Some are pretty obvious, such as the water slide in Koru Jungle. But some are more subtle, and you have to look around to find them, without knowing that they're even there.