Collectibles are paper objects that you pick up by taking the longer route where a path splits. They reveal more about the world of The Walk. You can tap on the Collectible icon within an episode map to view it.
Landscape features are notable items or scenery within each map. They will display as a small white square; only those near your current location on the map will be visible. “Scan” them by tapping the white square, revealing the landscape feature you have scanned. Scan all of them to get achievements and find hidden audio clips.