as a concept mckenzie wished to explore, the episode brought back the actor charlie tahan as jonathan crane / scarecrow, who portrayed the character on the first-season episodes: "the fearsome dr. crane" and "the scarecrow". mckenzie explained: "so we met his father dr crane in season 1. so we've taken our time; we're gonna come back now to his son. you know, in circumstances probably not best described now, his son takes on his father's mantle and becomes the fully-realized scarecrow. it's great. we're able to use this sort of fear toxin that scarecrow is able to summon. we're completely unafraid — or perhaps afraid but we still persist–in expanding the universe and our capabilities."