When the sisters are looking through the Book of Shadows for information on Troxa, they flip past the spell to Erase a Memory, which was one of several future spells from Morality Bites, supposedly meaning that they wrote it down when they returned to their own time.
Phoebe's premonition of Prue getting shot and falling dead on her side with her eyes still open is very similar to her premonition of Miles dying in the same way in season five's A Witch in Time.
Sight Unseen is an episode of The WB drama series, Charmed.
After the manor is burglarized, Prue becomes obsessed with learning more about the elusive evil force that is hunting her, while Piper and Phoebe believe its just the work of an over active imagination. Meanwhile, Cole discovers that the demon Troxa is stalking the Halliwell sisters, but unknown to all, he isn't the only one doing the stalking. Also, Piper and Leo try to get by the fact that the Elders are watching them sleep together and orb Leo out every time.
