First time one of the Charmed Ones (Phoebe) learns about white lighters. Phoebe is asked to keep it a secret from her sisters.
In this episode Leo calls his bosses "the Founders" - yet in every following episode they're called the Elders.
This is the first episode where no demons appear - though they are mentioned.
Prue is shown using her power to move multiple objects at once when she cleans up the attic. Previously (and often in future episodes) Prue would only be able to move an object she was looking at/focusing on.