Updated: September 09, 2016

The production basis of the show was the large number of period dramas made by the 20th Century Fox film company. Even black-and-white shots of the Titanic sinking were tinted to fit them into this color production. Only a few actors were costumed for a given episode, interspersed with cuts of great masses of people similarly dressed from the original features. The plots were not noted for historical accuracy, nor was continuity given much concern: in "Rendezvous With Yesterday" (episode 1) Tony states that he was born in 1938, but in "The Day The Sky Fell In" (episode 4), he states he was 7 years old when Pearl Harbor was bombed, and so would have been born in 1934.

Certain episodes featured aliens who wore costumes and carried props originally created for other Irwin Allen television and movie productions. Prop sets were similarly re-used. Only in episodes 18, 24, 28, 29, and 30 did aliens appear; only the second and third of these were set in the far future.

The Titanic-based premiere episode, "Rendezvous with Yesterday" (a re-edit of the original series pilot 2), was well written, and featured good production values, but Captain Smith of the Titanic was called "Malcolm" rather than "Edward" or "EJ". The names of the secondary officers are also fictitious and do not reflect the actual officers of the Titanic, though Walter Lord's best-selling book A Night to Remember had been available for nine years.

The prop computer looked realistic because it was actually an array of memory modules from the Air Force's recently decommissioned SAGE computer.

The theme for The Time Tunnel was composed by John Williams (credited as "Johnny Williams"), who would go on to become one of film's most celebrated composers - Williams also scored the pilot episode. GNP Crescendo later released an album featuring Williams's work and the score composed by George Duning for the episode "The Death Merchant."

The series won an Emmy Award in 1967, for Individual Achievements in Cinematography. The award went to L.B. "Bill" Abbott, for his photographic special effects.