Davies based the episode on the traditional disaster film format. He was highly influenced by the 1972 film "The Poseidon Adventure": he considered " the spaceship upside down" before cutting the concept for monetary constraints; and the character of Foon Van Hoff (Debbie Chazen) was heavily based on Belle Rosen (Shelley Winters). He diverged from the trope in its climax; the format of "Doctor Who" dictated the requirement of an antagonist: Max Capricorn, whose plan was to sabotage the ship as part of an insurance scam. Davies based the portrayal of Kansas in the 1939 film "The Wizard of Oz" as an analogue for Sto.