|For a complete plot of Once in a Blue Moon, go here.|
- Alyssa Milano as Phoebe Halliwell
- Rose McGowan as Paige Matthews
- Holly Marie Combs as Piper Halliwell
- Brian Krause as Leo Wyatt
- Nick Lachey as Leslie St. Claire
- Joel Swetow as Alpha
- Patrice Fisher as Beta
- Ian Anthony Dale as Gamma
- T.J. Thyne as Danny
- John Ross Bowie as Marcus
- John de Lancie as Odin
- Kerr Smith as Kyle Brody
- Paige made vanquishing potions for whoever or whatever was attacking whitelighters.
- Piper made potions for Leo if they (as Blue Moon Beasts) would attack him.
- The Charmed Ones threw dispossession potions to dispossess Leo.
- Orbing: Type of Teleportation used by Paige, Leo, Marcus and Odin.
- Telekinetic Orbing: Used by Paige to orb ice cream to her and to orb away a Crystal. She also orbed a television towards a possessed Leo.
- Molecular Combustion: Piper accidentally blew up a chandelier, a toaster and a vase. She later used it to blow up the smoke alarm in the kitchen.
- Hovering: Used by Danny to hover while meditating.
- Healing: Used by the Elders to heal Danny and Marcus.
- Illusion Casting: Used by an Unseen Force to make Leo see the Creature Head.
- Optical Energy Blasts: Used by the Avatars to vanquish the Possessor Demon and his tribe.
- Shimmering: Type of Teleportation used by a Possessor Demon.
- Teleportation Manipulation: Used by the Avatars to prevent the Possessor Demon from teleportating.
- Possession: Used by the Possessor Demon to possess Leo.
- Electrokinesis: Used by Leo (while being possessed) to attack Piper and the Elders. They also used it to attack him and to attack the Charmed Ones (as Blue Moon Beasts).
- Remote Orbing: Used by Odin to orb Leo back to Magic School.
- Molecular Immobilization: Used by Piper to freeze the Possessor Demon in mid-teleportation.
- Crystals - The Charmed Ones wanted to use the Crystals to set a trap for whoever or whatever attacked Whitelighters. Since they turned into the Beasts who attacked them, Marcus trapped them in the cage before he fainted.
- Blue Moon: A a phase that traditionally loosens the bonds of magic, on the three days when the blue moon rises. It can wreak havoc with all magical forces, causing witches' powers to become erratic and unpredictable or even ineffective.
Notes and Trivia
- The WB used the promo title Blue Moon.
- The WB use clips of the big bad wolf from "Happily Ever After" in their trailer for this episode.
- Instead of using makeup effects, computer generated effects were used for the beasts, which cost less money.
- Piper previously transformed into a beast under the full moon in "The Wendigo".
- In this episode, it's hinted that Magic School is located somewhere near the Golden Gate Bridge, as the sisters look through the windows and see it. It is also believed to be floating in the sky.
- This is the first time since "Oh My Goddess! part _" that Piper actually refers to Leo as her husband, while talking to the Avatars at the end of the episode.
- This marks the sixth and final appearance of Nick Lachey as Leslie St. Claire.
- This is the first time Piper uses her powers without her hands and only her mind. She claims that she was angry and reminds us that their powers are tied to their emotions.
- Phoebe's premonition powers seen to be affected by her extensive sensitivity.
- The title is a reference to the term "Once in a blue moon", which refers to something happening very seldom.
- The sisters transforming under the Blue Moon is similar to the fictional portrayal of werewolves transforming under the full moon, similar to the Wendigo.
- The ice cream Paige is eating is Ben & Jerry's Phish Food which is known to be Rose McGowan's favorite in real life.
- When Piper is about to explain about Leo, Paige orbs ice cream to the table she starts to take off the lid, but in the next shot she has the lid off and is eating it already. She also asks for three spoons, but only one spoon is shown.
- When Phoebe talks to Leslie about him leaving, her arms change between shots from hanging by her sides to her hands clasped together in front of her.
- Phoebe: It wasn't demonic, it was just that time of month. Besides it won't happen for another 50 years!
- Piper: Yeah. By that time we will be a menace to our rest home!
- French: Lune bleue (Blue Moon)
- Italian: Notti di luna blu (Blue Moon Nights)
- Czech: Když vyjde modrý měsíc (When Blue Moon Comes Out)
- Slovak: Za svitu modrého mesiaca (At the Shine of the Blue Moon)
- Serbian: Jednom u plavom mesecu (Once in a Blue Moon)
- Spanish (Spain and Latin America): Noches de Luna Azul (Blue Moon Nights)
- German: Im Bann des blauen Mondes (Under the Blue Moon's Spell)
- Hungarian: Amikor feljön a kék hold (When the Blue Moon Arrives)
Styx Feet Under
Someone to Witch Over Me
| Episodes: Season 1 - 2 - 3 - 4 - 5 - 6 - 7 - 8|
Comics: Season 9 - 10