What is unusual about the dialogue in the episode 'The Invaders'?

The unusual feature of the dialogue in “The Invaders” is that the episode has almost no dialogue.

The story follows an unnamed woman living alone in a remote cabin who is attacked by tiny astronauts from a miniature flying saucer. Agnes Moorehead carries nearly the entire episode through facial expressions, movement, cries, and physical reactions. Her character never speaks, making the performance unusually dependent on silent-film-style acting without actually turning the episode into a silent film.

There is a small qualification behind the common trivia answer. The episode is not literally dialogue-free: Rod Serling provides his usual narration, and director Douglas Heyes supplies the voice of one of the tiny invaders near the ending. The invader's speech reveals that the apparent aliens are actually astronauts from Earth, while the woman belongs to a race of giants on another planet.

Written by Richard Matheson and directed by Heyes, “The Invaders” originally aired on January 27, 1961. Its near-silent structure is one of the boldest formal experiments in the original series.