Memories of Irwin Allen!
Irwin Allen produced quite a number of Sci-Fi shows:
Voyage To The Bottom Of The Sea.
Lost In Space
Time Tunnel
Land of The Giants
The Towering Inferno
The Poseidon Adventure
Amongst the few. He had a nickname "The Master of Disaster" for his films.
The concept behind the Time Tunnel is this huge secret government project that takes place under the Nevada desert in 1968. The tunnel itself is this huge tunnel like thing that is connected to a huge power grid and lots of early computers. The government decides to shut the project down and one of the scientists decides to make a renegade trip in it. Well, of course they can't get him back to the present time, so they send another scientist after him. Now they can't get both of them back. We now have something to base the show on. So show after show, the scientists in the tunnel base spend their time trying to retreive the two time travelers. But due to lack of power, malfunctions, etc;but they
can't. The show ended after only two seasons with out travelers still bouncing around time. The show ran in the 1967-68 season on ABC.
Another thing that Irwin Allen was known for is to use stock footage in his television shows to keep the cost down. He may use a old clip of maurauding indians, army legions, etc in his shows.