Oceanic Airlines: Pan-Oceanic flight is mentioned on a notepad when Scully searches the hotel room.
Time Travel: A man came from the future and tries to prevent the invention which gets him to the episode's present time.
Well-Intentioned Extremist: Older Jason Nichols is trying to stop his younger self and others from creating a compound that allows time travel. It turns out, a society where everyone can know what's happened (and what will happen) is one past the Despair Event Horizon. Older Jason defines it as a world without hope.