Ideas for a D&D game 40 years ago

Years ago I ran a D&D campaign where the characters were defeated, and sent forward in time several thousand years by one of their foes. It was a chance to play some Gamma World style games.

I can barely remember how they got back but just thought of a much better way. There could have been a Cave of Wonders described to them where things like dragons would appear (in a post-apocalyptic future world), or bugbears or anything that would make them suspect that this might be a link to their past. 

As they fought through the bizarre defenders/residents of this cave they would indeed fight dragons and beasts they recognize, but would also fight bizarre future robots or men from the future with plasma rifles, etc. (or hybrids from an in between time). Maybe there would also be the wrecks of great ships (with defenders and treasure,  airplanes (crumpled), spaceships, etc. 

Eventually they'd get to a subterrain super collider that had torn holes in spacetime in a giant spherical chamber with many growing and shrinking portals. Each one would be at the center of a storm in time where people and things could be pulled through.  Their problem would be just how to find where to go to go back to their time. 

Maybe disruptions in time would show up as different portals? Maybe a big bang with a flash of magic?

Maybe there is still a computer working they could negotiate with? Maybe it just wants to shut the collider off.