When the white dog "Tiffany" comes to the abandoned house for the first time, as she is climbing into the house, you can see a crew member down below spotting her as she climbs onto a high rail.
Benji's real name was Higgins and got his start as a regular cast member of sixties TV sitcom Petticoat Junction. Though he was retired shortly after the end of Petticoat Junction, Higgins later came out of retirement to launch a career in movies as Benji, starring in the first two films of the series (his offspring have carried on the legacy in subsequent films). Frank Inn was his trainer throughout his lifetime and began as an assistant trainer for Lassie.