Oh yes, it's a favorite of Emily's and mine--I wrote about it back when it first came on. Timeless got unfortunately canceled, but they did a TV movie to wrap everything up. I liked the fact that if they screwed up, it really did change time. Very well done, both in specific episodes and the overall arc.

I used to watch "Time Tunnel" as a kid, and I've caught a couple of episodes recently. Definitely similarities!