Hi Henry Read,
Any additional non-asset files are included in the OBB, not as separate files on /sdcard. You can access them without a path since the default is Content. In the case of packaging data in the APK, the OBB is actually embedded in the APK assets directory with a png extension to keep it from being additionally compressed. The OBB itself is a ZIP file so you can look at the contents with any ZIP utility if you want to see what was included.