What literary elements are used in "Visit to a Small Planet" and how do they enhance the story?
Gore Vidal's play was written for television rather than the stage. For this reason, the reader must be somewhat familiar with shooting jargon ('stock shot,' 'fade out...'), which often replaces stage directions.
The main character Kreton uses both implicit and explicit metaphors in his speech. He refers to people as "poor fragile butterfles - such brief moments in the sun," and later visualises their emotions (and the cat's) in colours - red for anger, purple for passion and black for death wishes. He can even picture people's desires or longings, such as General Powers polishing the extra stars on his sleeve in light of his "promotion."
The other characters are more "down-to-earth" but incarnate stereotypes: John and Ellen, the wistful young couple; Mrs Spelding, the finnicky domestic housewife; Mr Spelding, the opportunist social striver; General Powers, the hawkish military professional. This is appropriate as the play is a satire, or more specifically, a comedy of manners.
The final scene with Kreton's spaceship zigzaging erratically out of sight is also an implicit metaphor. Evidently, Kreton is a bit off his rocker, and the human race still has a long way to go....