Many modes of transit through superspace involve apparent physical travel over land
or through outer space. Through mishaps, other tangent-crossing vehicles (the larger the better) might have broken down, crashed or been abandoned along well-used routes and appear as wrecks.
Similar possibilities include enormous skeletons of time-lost beasts or roadside establishments founded by former travellers.
Tangent natives may or may not be able to see, recognise or use such locations.