The first season episode title "The Fourth Sister" considering they had a fourth sister all along.
The aforementioned horror movie line. In the episode "Chick Flick" which is an Affectionate Parody of slasher movies, Prue is the first one to get attacked by the psycho killer.
A series of strange coincidences involving Charmed and Professional Wrestling have been creeping up after the show ended:
The Pro Wrestling Episode "Wrestling With Demons". Think about this: Prue and Phoebe defeated Booker T and Scott Steiner, the two guys that would later win tag team championships together as part of TNA's Main Event Mafia.
The Nexus, the central point of powerful energy the Manor was built upon, becomes the object of Zankou's demonic ambitions in season 7 (and those of Paul Haas in early season 8). Furthermore, when demons get killed, they go to a desolate place aptly called the Wasteland, where they inevitably end up as food for a hungry serpent beast. Fast forward to 2010 where a Power Stable of young upstarts known as The Nexus start running amok in WWE, led by and centered around the ambitions of a man whose Finishing Move at the time is called the Wasteland.
Paige's appearance in the fourth season is that of Raven Hair, Ivory Skin and as noted on the main page, her Blood Knight tendencies have earned her the Fan Nickname "Raige" on the Television Without Pity recaps. Fast forward to 2012 where we have a WWE Diva named Paige with black hair and pale skin, known for being violent and aggressive. Slight bonus to that one: in Chris's first appearance he makes the comment of "Stone Cold Paige", in reference to her being frozen by the Titans. WWE's Paige was a guest on the podcast of wrestling legend "Stone Cold" Steve Austin where she openly admitted to being inspired by Austin. And the film Fighting with My Family (which is about Paige the wrestler) depicts her getting the name from the character in the TV show.
Piper's son Wyatt essentially became the plot of Season 6, in which it's revealed that he's destined to become the Above Good andEvil Overlord of a Bad Future unless someone's attempts to kill/convert him are thwarted. Fast forward to 2012 where we have a WWE Superstar named Bray Wyattnote portrayed by a former member of the aforementioned Nexus group for good measure who leads a creepy cult "family" and is implied to be a man possessed by an ancient demon, possibly Satan himself. Furthermore, Wyatt Halliwell was born inside the Manor, making him extra susceptible to a Face–Heel Turn thanks to the Manor's Nexus. The man implied to be Bray Wyatt's vessel is the previous character his wrestler portrayed as a former member of the Nexus stable.
When Phoebe says of Penny's six marriages,note This is a goof; Penny was engaged six times but only married four Cole says "I would have stopped at three". Phoebe would eventually be married three times across the series. And she would stop at the third one.
In "Enter the Demon" Piper is annoyed that Paige isn't taking her Charmed duties seriously, specifically her potions. Fast forward to "Siren Song" where Paige has been on a kick of hunting demons and experimenting with potions - which Piper complains about. Be Careful What You Wish For.
A meta case. Just before the fifth season started filming, Rose McGowan did an interview where she said it was odd that they didn't show Paige dating anyone at all in her first year. She ended the interview saying "I hope I get some action". This becomes hilarious if one watches an extra on the DVD - where Rose talks about how she'd have these one-shot raunchy scenes with interchangeable male actors. She then went to the producers and said "Paige isn't a ho!" - Be Careful What You Wish For indeed.
This show was inspired by the film The Craft, and one of the stars of that film, Rachel True, who is African-American, mocked Aaron Spelling for making the characters sisters, calling it an excuse to not cast any actresses of color. The 2018 reboot would give the sisters a Race Lift to become Latina/bi-racial. And that series would then be attacked for colorism - as only Melonie Diaz identifies as Latina.
Phoebe's future self is distinguished from her present self in both Seasons 2 and 7 by having near waist-length hair. Alyssa Milano did end up growing her hair to that length after the show ended, and it was even like that for the special features created for the Deluxe Edition boxset.
At the start of Season 4, Phoebe and Piper question how a whitelighter, who is basically an angel, could get someone knocked up, while a bitter Piper called Paige "half breed" for being half-witch, half-whitelighter. This becomes hilarious by the end of the season when Piper is revealed to be pregnant with her own half-witch half-whitelighter baby.
In "The Power of Three Blondes", Chris kisses Mitzy Stillman in a gambit to get the Stillmans to turn against each other and revert the Power of Three back to the rightful owners. Except, Mitzy is still under the identity of Phoebe Halliwell. So technically, in that moment, Chris was kissing his aunt, even if by this point he knew she was an imposter.
