Rex is played by Diesel vom Burgimwald with two other German Shepherds standing in for some of the stunts. Training with the dog continues on non-shooting days in preparation for future scripts. On set, Diesel gets treated like a proper movie star with his own trailer, chef and chauffeur.
There were actually 16 episodes filmed for Season 1 but only 13 aired. The remaining three were then used for the start of Season 2.