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.

Rod Serling invited viewers to submit a script. He was flooded with over fourteen thousand scripts, and he actually got around to reading five hundred 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 made up the phrase "sixth dimension" to use in season one's opening narration. William Self of CBS 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 thought he had come up with the term "The 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 U.S. Air Force pilots when crossing the day and night sides above the world.

Almost all of the men in season one, introduced by Rod Serling's opening narration, were described as being thirty-six years old.

Rod Serling was ranked number one in TV Guide's list of the "25 Greatest Sci-Fi Legends". (August 1, 2005)

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 television, on a studio soundstage, using a total of four cameras. The requisite multicamera set-up of the videotape experiment pretty much precluded location shooting, severely limiting the potential scope of the storylines, 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); and The Twilight Zone: Long Distance Call (1961); and then transferred to film for broadcast, which saved the producers about five thousand dollars per episode.

The oft-parodied high-pitched guitar melody riff in the theme music was played by Howard A. Roberts.

The Twilight Zone: The Dummy (1962) is routinely voted the scariest series episode by critics.

Although the phrase "Submitted for your approval" from Rod Serling's opening narration has come to be closely identified with the show (and is often used by Serling impressionists), it is only heard in three episodes: The Twilight Zone: Cavender Is Coming (1962), The Twilight Zone: In Praise of Pip (1963), and The Twilight Zone: A Kind of a Stopwatch (1963). At the end of the parallel as well.

All episodes in seasons one, two, three, and five were thirty minutes in length. Episodes in season four (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.

In what is generally regarded by fans as the most hated episode of the series, The Twilight Zone: Cavender Is Coming (1962), starred Jesse White and Carol Burnett in what was supposed to be a spin-off episode for a sitcom about a bumbling guardian angel. The episode was videotaped and had a laugh track.

Other than 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 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.

A comic book version of this series, "hosted" by the artistic image of Rod Serling, ran until 1982, seven years after the real Serling had died.

Rod Serling was often seen with a cigarette during the introduction. One of the show's sponsors was the Liggett & Myers tobacco company and Serling served as on-screen spokesman for their product, Chesterfield cigarettes, during his "tune in next week" spot at the end of each episode. The American Tobacco Company, a later sponsor, insisted that he always be seen with a cigarette, although Serling refused to plug their brand (Pall Mall) on-screen.

Ranked number eight in TV Guide's list of the "25 Top Cult Shows Ever". (May 30, 2004)

Of the three "The Twilight Zone" television 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.

This became a landmark television series. It was beloved by critics and the public as well. Rod Serling's follow-up series Night Gallery (1969), and other shows he did after that, never had the same impact.

Michael Jackson sampled Serling's narrations in his song "Threatened". He sampled from several episodes, but the two most noticeable ones are "It's a Good Life" and "In His Image".

On August 11, 2009 the U.S. Postal Service issued a pane of twenty 44-cent commemorative postage stamps honoring early U.S. television programs. A booklet with twenty picture post cards was also issued. On the stamp honoring this show, is a picture of its creator, host, and narrator Rod Serling. Other shows honored in the "Early TV Memories" issue were: The Adventures of Ozzie and Harriet (1952), Alfred Hitchcock Presents (1955), The Dinah Shore Show (1951), Dragnet (1951), The Ed Sullivan Show (1948), The George Burns and Gracie Allen Show (1950), Hopalong Cassidy (1952), The Honeymooners (1955), The Howdy Doody Show (1947), I Love Lucy (1951), Kukla, Fran and Ollie (1947), Lassie (1954), The Lone Ranger (1949), Perry Mason (1957), The Phil Silvers Show (1955), The Red Skelton Hour (1951), The Milton Berle Show (1948), The Tonight Show (which began as Tonight! (1953)), and You Bet Your Life (1950).

The Twilight Zone: The Monsters Are Due on Maple Street (1960) is very similar to "Lord of the Flies" by William Golding; right up to the scene where the towns people kill their neighbor.

Rod Serling was able to tap into the fears held by the public. This he achieved by covering various themes in "The Twilight Zone," like paranoia, bigotry, social and moral injustice etc.

Although "The Twilight Zone" wasn't the first TV show of its kind, it is the one by which most others are compared.

Amongst the many classic episodes are the following: The Twilight Zone: The Lonely (1959) The Twilight Zone: Perchance to Dream (1959) The Twilight Zone: The Purple Testament (1960) The Twilight Zone: Long Live Walter Jameson (1960) The Twilight Zone: The Howling Man (1960) The Twilight Zone: A Hundred Yards Over the Rim (1961) The Twilight Zone: Deaths-Head Revisited (1961) The Twilight Zone: In Praise of Pip (1963) The Twilight Zone: Nightmare at 20,000 Feet (1963) The Twilight Zone: Living Doll (1963)

"The Twilight Zone" is sometimes compared with The Outer Limits (1963) and vice versa. However, the former show covers more in the way of Fantasy. The latter is pure Science Fiction.

On May 11, 2018, not long after The Twilight Zone (2019) was picked up for CBS All Access, CBS picked the following as the 10 most terrifying episodes of the original series. The Twilight Zone: Nightmare at 20,000 Feet (1963) The Twilight Zone: Time Enough at Last (1959) The Twilight Zone: Living Doll (1963) The Twilight Zone: Eye of the Beholder (1960) The Twilight Zone: It's a Good Life (1961) The Twilight Zone: The Monsters Are Due on Maple Street (1960) The Twilight Zone: Twenty Two (1961) The Twilight Zone: Five Characters in Search of an Exit (1961) The Twilight Zone: The Masks (1964) The Twilight Zone: The Hitch-Hiker (1960)

In 1958 the WW2 submarine movie Run Silent, Run Deep starring Clark Gable and Burt Lancaster was released. Eight members of the cast would later star in The Twilight Zone. These include Jack Warden, Don Rickles, Joe Maross, Mary LaRoche, Ken Lynch, HM Wynant, Nick Cravat, and John Close.