In his commentary track for the 2001 Anchor Bay DVD release, director Val Guest stated that the sound of church bells heard at the very end of the American version had been added by distributor Universal, in order to suggest that the emergency detonation had succeeded and that the Earth had been saved. Guest speculated that the bells motif had been inspired by the film "The War of the Worlds" (1953), which ends with the joyous ringing of church bells after the emergency (and a nuclear explosion). But Guest maintained that his intention was to always have an ambiguous ending.