Rod Serling wanted Richard Egan to do the narration because of his rich, deep voice. However, due to strict studio contracts of the time, Egan was unable to. Serling said, "It's Richard Egan or no one. It's Richard Egan, or I'll do the thing myself," which is exactly what happened.
Series creator Rod Serling made up the phrase "Sixth Dimension" to use in season one's opening narration. William Self of CBS-TV asked him what was the fifth dimension (given that dimensions one through three are exemplified by a line, a plane, and a cube, respectively, and the fourth is time). Serling answered, "I don't know. Aren't there five?" He then changed the narration to "There is a fifth dimension..."
Rod Serling invited viewers to submit a script. He was flooded with over 14,000 scripts, and he actually got around to reading 500 of them. However, only two were any good, and he couldn't use them because they didn't fit the format of the show.
Rod Serling thought he had come up with the term "Twilight Zone" on his own (he liked the sound of it), but after the show aired he found out that it is an actual term used by Air Force pilots when crossing the day / night sides above the world.
Due to budgetary constraints in its second season, the network decided to cut costs by shooting some episodes on videotape rather than film. Because videotape was a relatively primitive medium in the early 1960s, the editing of tape was next to impossible. Thus, each of the six episodes was "camera-cut" as in live TV, on a studio sound stage, using a total of four cameras. The requisite multicamera setup of the videotape experiment pretty much precluded location shooting, severely limiting the potential scope of the story-lines, and so the short-lived experiment was ultimately abandoned. The limitations of using videotape (e.g., it could not be edited as cleanly as film and its visual quality was poorer) led the network to switch back to film for the rest of the series, despite the greater cost. The six videotaped episodes were titled: The Twilight Zone: The Lateness of the Hour (1960); The Twilight Zone: Static (1961); The Twilight Zone: The Whole Truth (1961); The Twilight Zone: The Night of the Meek (1960); The Twilight Zone: Twenty Two (1961); The Twilight Zone: Long Distance Call (1961) and then transferred to film for broadcast, which saved the producers about $5,000 per episode.
Other than series creator, host and narrator Rod Serling, Robert McCord was the only actor to appear in all five seasons. In second place are Jack Klugman, John Anderson, Jon Lormer and Vaughn Taylor, who each appeared in four seasons. Klugman and Taylor both appeared in the first, third, fourth and fifth seasons, Anderson appeared in the first, second, fourth and fifth seasons and Lormer appeared in the each of the first four seasons.
All episodes in Seasons 1, 2, 3 and 5 were 30 minutes in length. Episodes in Season 4 (airing from January to May 1963) were one hour in length due to CBS' switching the show's available time-slot where only an hour could be taken.
Of the three "Twilight Zone" TV series over the years, this is the only one which does not include Rod Serling's image during the opening credits. Of course, this is the only one of the series to have the opening voice-over performed by Serling.
It was due to creator Rod Sterling's excessive smoking, that he was often seen with a cigarette during the introduction. Also, since one of the show's sponsors was the Liggett & Myers tobacco company, Serling served as an on-screen spokesman for their product, Chesterfield cigarettes, during his "tune in next week" spot at the end of each episode. The American Tobacco Co., a later sponsor, insisted that he always be seen with a cigarette, although Serling refused to plug their brand (Pall Mall) on screen.