Rod Serling wrote a scene for the crash landing of the spaceship in the original script, but it was determined to be too expensive to film. The script was subsequently modified, and the crash was described by Mr. Serling in the opening narration.
Although not in the script, Douglas Heyes told Rod Taylor to jump through the bar window because he felt his character was in such a fever pitch it only made sense. Rod Serling saw the scene and liked it enough to approve the change.
Rod Serling wrote the character Forbes was terrified throughout but Douglas Heyes suggested the sensation of being pulled from existence should be euphoric.
Richard Matheson's first credit on The Twilight Zone, as the author of the short story on which the episode was loosely based.