It's not the world's first freefall drop on a coaster. A duelling coaster known as Winjas (Winjas Fear and Winjas Force I think) at Phantasialand has the element. Both tracks feature a small (smaller than Th13teen) freefall drop, after which, the track rise back up again and continues. Look it up on rcdb, etc. Also, this image shows the track layout nicely.If you want to be pedantic, you could say Th13teen is the world's first coaster to feature a freefall drop which acts as a switchback. However, when you think it about, all the SWs have featured pendantic-ness when you considering their world first-ness.EDIT: Also, just remembered, I'm not sure if this is true, but a Gerstlauer ride has a track which slowly drops in it's station area. Only something I remember hearing; again, not sure if it's true or not.