Land of the Giants

Despite having a working time machine and 3-4 thousand years of technological advancement, the time travellers don't know they missed Earth and are an alien planet?!?

The title of the episode has nothing to do with nor any relevance to the episode.

The powers of the time travellers vary wildly: sometimes they walk, sometimes they teleport. Sometimes they simply raise their hand and freeze time, sometimes they need the medallion. Sometimes their force fields protect them (even if they aren't aware of an attack), sometimes they don't (when Steve uses the dart on Olds).

Despite being almost three thousand years in the future, the time travel chamber has the same swirly-radar screen thing that the Spindrift pilot cabin had in the first season.

Supposedly alien planet: A drug specifically named "sodium amo-barbitol"