The High Guard ships being held prisoner at Tartarus are powerful entities from the past. In Greek mythology the Titans, who were the gods before Zeus and company were born and overthrew them, are imprisoned in Tartarus.
Michael Hurst (Ryan) and Kevin Sorbo (Captain Dylan Hunt) have worked together on Hercules: The Legendary Journeys (1995), playing Iolus and Hercules, respectively. Also, Christopher Judge (Avatar of The Achilles), Matthew Walker (Secretary Falin) and Lexa Doig (Andromeda) end up working together, a couple of years after this episode, on seasons 9-10 of Stargate SG-1 (1997).
When Ryan (Michael Hurst) tells Dylan (Kevin Sorbo) that the ships are being kept at Tartarus, Dylan says the name and pauses for a moment. When Ryan asks what's wrong, Dylan answers "Deja vu." This is likely a reference to the show Hercules: The Legendary Journeys (1995). In the episode The Other Side (1995), Hercules (Kevin Sorbo) and Iolaus (Michael Hurst) travel through Tartarus together to rescue Persephone.
When Rommie offers to recite a Limerick she starts "There was an old man from Nan...". The full limerick is: "There was an old man from Nantucket, Who kept all his gold in a bucket, Then his daughter Nan, Ran away with a man, And as for the bucket, Nan tuck it."