The base for Project Tic-Toc is a huge, hidden underground complex in Arizona, 800 floors deep and employing more than 12,000 specialized personnel.

[1] The directors of the project are Dr. Douglas Phillips (Colbert), Dr. Anthony Newman (Darren), and Lt. General Heywood Kirk (Whit Bissell).

The specialists assisting them are Dr. Raymond Swain (John Zaremba), a foremost expert in electronics, and Dr. Ann MacGregor (Lee Meriwether), an electrobiologist supervising the unit that determines how much force and heat a time traveler is able to withstand.

Episodes two through 23 begin with the following narration (voiced by Dick Tufeld): Two American scientists are lost in the swirling maze of past and future ages, during the first experiments on America's greatest and most secret project, the Time Tunnel.

General Kirk, Ray, and Ann in the control room are able to locate them in time and space, observe them, occasionally communicate with them through voice contact, and send help.

The series was abruptly cancelled in the summer of 1967 by ABC, before they were able to film the episode in which Tony and Doug are safely returned to the Time Tunnel complex.

Episode 26 ("Attack of the Barbarians") explores the scenario of one of the time travelers falling in love with someone from the past: Tony and the Princess Serit, daughter of Kublai Khan.

The production used sets, stock footage, and props left over from the large number of period dramas made by the 20th Century Fox film company.

For the pilot episode, a large control-room set was built, and a longer Time Tunnel was created using optical matte shots.

After the pilot episode, location changes occurred for the production of the series; Colbert and Darren shot their scenes in another studio, on the 20th Century Fox backlot, or on location, while those who portrayed the Time Tunnel personnel filmed all their scenes on a revised and smaller Time Tunnel control-room set (due to the production having to use a smaller sound stage than used during the pilot filming).

Some episodes featured space aliens who wore costumes and carried props originally created for other Irwin Allen television and film productions.

The names of the secondary officers are also fictitious, though Walter Lord's best-selling nonfiction book about the event, A Night to Remember, had been released nine years earlier.

GNP Crescendo later released an album featuring Williams' work and the score composed by George Duning for the episode "The Death Merchant".

Senator Leroy Clark (Gary Merrill) arrives in Arizona to evaluate Project Tic-Toc, which is researching time travel.

To prove time travel is possible, Dr. Tony Newman secretly enters the Tunnel and lands aboard the Titanic the day before it sinks.

A present-day British Army officer, General Southall, is brought to the time tunnel so the team can establish Tony and Doug's location.

Tony and Doug hide and accidentally find a secret passage to the estate's upper floors, where the owner, nobleman Galba, offers to protect them from the Germans.

Project HQ utilizes the services of a paranormal researcher Dr. Steinholtz (John Hoyt), who suggests zapping Tony with 1,000,000 volts of electricity for one millisecond through the Tunnel to force the ghost out.

The newly retired Time Tunnel staff doctor, Dr. Benjamin Berkhart, insists on going back to save Tony and Doug, and help the wounded American sailors.

They are in a futuristic complex run by a curator (Michael Ansara), who has begun to compile all the data of the history of the Earth by extracting the memories of all its historical figures.

Unable to attack the aliens effectively with the resources at hand, Tony, Doug, and the British soldier fetch grenades and gunpowder from Khartoum.

Leinster used four of the main characters: Tony Newman, Doug Phillips, General Kirk, and Ann MacGregor and initial antagonist Senator Clark.

Also differing form the series, Senator Clark, here demands the end of Project Tic-Toc out of fear of [grandfather paradox]] which could result in the erasure of the current timeline.

The DVD box sets include nearly all full-length, uncut and unedited original network prints, but one episode, "Chase Through Time", was edited.

The highlight of this package is the colorful 12-page booklet which showcases original storybook artwork of the record's episode with the intrepid time travelers being terrorized by rampaging dinosaurs and angry cavemen.

Bally Manufacturing created a pinball machine called Time Tunnel[15] in 1971 based loosely on the TV series, but production was stopped due to copyright infringement.

[16] Big Finish Productions released a box set of audio dramas, entitled Irwin Allen's The Time Tunnel: The Nightmare Begins in February 2025.

When the team is almost captured, two members switch to German uniforms and pretend to be Colonel Klink and (Sergeant) Schultz, complete with fake documents.

Allen's wife, Sheila, and two producers of the 2002 FOX remake (Kevin Burns and Jon Jashni) began work on the new pilot.

Featuring a mock up of the original Project Tic-Toc set and animated Time Tunnel-style title sequence, the main characters are also called Doug and Tony.