Pathfinder was when Reg goes nuts in the holodeck trying to get the communications relay set up to talk to Voyager, and manages to get it going just in time, before he is hauled off and court-martialed. Troi visits to keep him off the ledge.
As to the old serials that Chaotica spoofs, the main one it emulates is Flash Gordon with Buster Crabbe, which I loved, and have on DVD. But I don't love many other ones the same way.