From WIkipedia:
It's About Time is an American fantasy-based comedy TV series that aired on CBS for one season of 26 episodes in 1966–1967. The series was created by Sherwood Schwartz, and used sets, props and incidental music from Schwartz's other television series in production at the time, Gilligan's Island.
It's About Time was virtually two different series aired under the same title. The first version of the series saw two astronauts, Mac (Frank Aletter) and Hector (Jack Mullaney), accidentally break the speed of light, and get thrown back in time to prehistoric days. There, they have to adjust to living with a cave family led by Shadd (Imogene Coca) and Gronk (Joe E. Ross). (In the pilot Coca's name was credited as Shag; when CBS censors realized that term held another meaning in the youth culture they changed her name to 'Shadd'.) Their children were 18-year-old Mlor (Mary Grace) and 12-year-old Breer (Pat Cardi). The chief of the tribe, Boss (Cliff Norton) and his right-hand man Clon (Mike Mazurki) were always suspicious of the astronauts.
Approximately halfway through the season, the show's lower-than expected ratings resulted in the producers suddenly retooling the series by having the astronauts repair their space capsule and return to 1967 with the cave family in tow. The remainder of the season was spent with Shadd, Gronk and their family adjusting to life in the 1960s, reacting to the unfamiliar surroundings, setting up home in 20th-century New York City. A typical episode had Gronk and Shadd learning to write their names and signing them for many salesmen who brought "presents", which had to be paid for. The astronauts could not convince their superiors at the Space Center that cave-people were living with them.
Created by Sherwood Schwartz
Starring
Frank Aletter
Jack Mullaney
Imogene Coca
Joe E. Ross
Theme music composer
Gerald Fried
George Wyle
Sherwood Schwartz
Country of origin United States
No. of episodes 26
Production
Running time 30 minutes per episode
Broadcast
Original channel CBS
Original run September 11, 1966 – April 2, 1967