Doug and Tony are thrown to a mining town in 1910, just after a cave-in traps 200 men below ground. No one wants to help because they fear Halley's Comet means the end of the world anyways.
There's just something so joyously insane about "Time Tunnel" episodes that it makes me smile. Sort of a combination of parallel world "Golden Compass" pseudo-reality and the vision of two teenage science nerds who have just smoked their first doobie in the basement.
This installment is no different. Everything but the kitchen sink is thrown in. The turn-of-the-century town, frightened by Halley's Comet has decided to isolate itself from the world like a a bad Stephen King novel, the local astronomer has a remarkable ability to predict the second that the comet's tail will vanish, and an unknown non-reflective gravitational body is working it's magic. Need more? Back at the complex, somehow aspects of the comet threaten to come through the Time Tunnel and Ann (Lee Meriwether) yanks power cords out of the Tunnel master controls and re-starts a man's heart.
Irwin Allen made a lot of throw-away TV, but this is one of his better ideas - the production values are decent (at least when they can use existing sets like those for westerns), no one scene can bother you before you are off to the next, and another crazy plot twist is always just around the corner. Is it good TV? Not really, but it's as good a value as a roller coaster ride. I will note that this is one of the best-written episodes, others are FAR crazier.