The French Mistake is the 15th episode of Season 6. It aired on February 25th, 2011.
Raphael launches an attack on Castiel and his allies, sending a particularly frightening angelic hitman after Balthazar, Sam and Dean... In an effort to protect the brothers, Balthazar sends them to an alternate universe where they are the stars of a TV show called “Supernatural” and they are actors named “Jensen Ackles” and “Jared Padalecki.” The brothers are confused when Castiel appears to be a tweet-happy actor named Misha Collins and Sam is married to "Ruby".
Dean and Sam are doing research at Bobby’s House when Balthazar appears. He says that Raphael is aiming to kill all of Castiel’s allies and affiliates so he gives them a key and sends them to an alternate reality to keep them out of harm's way. Supposedly, the key opens a door where he has stored the stolen Angelic Weapons of Heaven, which will help Castiel to retain control in Heaven.
When they appear in the alternate reality, Sam and Dean find themselves on the set of "Supernatural"- a show that appears to be about their lives and where everyone mistakes them for the actors Jensen Ackles and Jared Padalecki. They try to contact Castiel, but instead, encounter Misha Collins, who plays Castiel on the TV Show. Taking refuge in Jensen's luxurious trailer, they do some research about Jensen and Jared, and Dean is horrified to learn that Jensen was a soap opera star. Dean suggests they try doing the same spell Balthazar did in order to get them back to their own reality.
Discouraged that there are no 'real' saints' bones or other items they need on the set of Bobby’s house, Sam and Dean have the actors' driver, Clif Kosterman, take them to Jared's place, which turns out to be a large ostentatious mansion with a tanning bed in the living room and an alpaca in the backyard. Sam and Dean are shocked when Ruby - or rather the actress who plays her - appears and kisses Sam, who she believes to be her husband, Jared. After Genevieve Padalecki heads out to a charity function for the International Otter Adoption Fund, Sam and Dean go online and purchase some saints' bones for rush delivery using Jared's credit cards (they max out at least one). Dean then spends the night on Jared's couch, while Sam alternates between surfing the internet for signs of the supernatural activity and sleeping with Genevieve.
The next morning, Clif drives them to the airport to pick up the rush delivery before taking them back to the set. They have to try and act in a scene which ends badly after many takes, but in between takes, they try and do the spell. When nothing happens, they come to the conclusion that in this reality there is no real supernatural, no magic.
Back on set, the angel hitman Virgil appears and tries to vanquish Dean with his angel powers. He, too, is devoid of powers in this reality, so Sam and Dean are able to take him in a fight and start pummeling him on the set of the Dragon's hideout from ‘Like A Virgin’. The rest of the crew intervenes, however, and during the resulting scuffle Virgil pickpockets the key Balthazar gave Sam before running away.
The crew of the show is now suspicious because "Jared" and "Jensen" are behaving out of character. Normally they don't speak to each other, they came in with a mysterious package (the saint's bones) which the crew believes are either drugs or black market organs, and now they've beaten up Virgil, who everyone believes to be an extra. Director Bobby Singer calls showrunner Sera Gamble and suggests that they get Eric Kripke to come to Vancouver and talk to them. Sera reluctantly agrees, although Kripke is sequestered in a cabin writing the script for "Octocobra." Meanwhile, Virgil takes Misha hostage and kills him so he can use his blood to contact Raphael.
Bob confronts Sam and Dean, and they drop the pretense of being Jared and Jensen and tell him that they quit, making Bob shocked. Dean says that at least in their world they make a difference. They then go back to Jared's house and learn from Genevieve that Misha is dead, so they go to the scene. A witness states that the killer was speaking to "Raphael," and they learn from the relayed conversation that Virgil is trying to get back to their reality. While they wait for him on the set, Dean suggests to Sam that maybe if they get stuck in this reality, Sam's life would be better. But Sam disagrees because back in their world they do matter, and he doesn't like that in this world they aren't even brothers.
Virgil returns on set just as Kripke arrives to speak to them, and the angel goes on a killing spree, killing Eric Kripke, Bob Singer, Kevin Parks, and Lou Bollo before Sam and Dean manage to knock him out and get the key. Just as Sam has the key in hand, Raphael activates the nearby gate between the worlds, and they land back in their own reality.
Raphael - now in a female vessel -demands the key, but Balthazar arrives and reveals that the key and Sam and Dean's journey was all a ruse to distract Raphael. He threatens them, but Castiel arrives and reveals that he now has all the Angelic Weapons. He threatens to kill Raphael, and Raphael leaves. Castiel then returns Sam and Dean to Bobby's house, promising to reveal more of what is happening in Heaven soon. Back at home, Sam and Dean reflect that they are now back in their old, crummy house with no money, but at least they're talking to each other.
- Jared Padalecki as Sam Winchester
- Jensen Ackles as Dean Winchester
- Misha Collins as Castiel and Himself
- Sebastian Roché as Balthazar
- Lanette Ware as Raphael
- Carlos Sanz as Virgil
- Micah A. Hauptman as Eric Kripke
- Brian Doyle-Murray as Robert Singer
- Jason Bryden as Kevin Parks
- Art Kitching as Serge Ladouceur
- Lou Bollo as Himself
- Garwin Sanford as Jim Michaels
- Phil Hayes as Clif Kosterman
- Genevieve Padalecki as Herself
- Unknown actress as Sera Gamble (voice only)
- Antagonists: Virgil and Raphael.
- The title of the episode is a reference to the Mel Brooks comedy, Blazing Saddles, where characters attend the film's premier and crash through a Hollywood set with actors performing a musical number seemingly entitled "The French Mistake" echoing Sam and Dean crashing through the window into the set in the parallel reality.
- The premise of this episode was revealed during "Salute to Supernatural San Francisco" when Jensen Ackles and Jared Padalecki explained it during their panel.
- The tweets Misha Collins made in this episode were actually tweeted in real life.  
- This episode pokes fun of reality as Jensen Ackles, Jared Padalecki and Misha Collins play Dean Winchester, Sam Winchester, and Castiel respectively. Furthermore, Genevieve Cortese, the actress that portrayed Ruby, is married to Jared Padalecki.
- Featured a clip of Jensen Ackles from his stint on the soap opera Days of Our Lives.
- There are numerous references to this being the sixth season.
- It is said throughout the episode that Jensen and Jared do not get along. In real life, they are best friends.
- This is the final episode this season to not feature Bobby Singer, though much of it takes place in his house.
- Dean's line, "If I hear one more conversation about hockey, I'm going to puke" is ad-libbed.
- The episode features a real copy of The Official Supernatural Magazine (the copy in question is issue 11) that Dean picks up and refers to in Jensen's trailer.
- When Dean shows Sam the Supernatural Magazine he says "Nice blue steel Sam" a reference to the movie Zoolander.
- Dean's line, "No hell below us, above us only sky." is a line from John Lennon's song, Imagine.
- Dean's line (seeing Raphael as a lady) "Dude looks like a lady." is in reference to an Aerosmith song of the same title.
- Misha regards this episode as one of his favorites, alongside "Baby".
- This is the first episode in the series to be set in Canada. The second episode is "Celebrating The Life Of Asa Fox".
- Genevieve: "Oh My God, oh my god, oh my God!"
- Dean: "You married fake Ruby?"
- Dean: "What kind of douchebag names a character after himself?"
- Dean: "Why would anyone want to watch our lives?"
Sam: "According to the interviewer, not very many people do."
- Dean: "Oh crap. I'm a painted whore."
- Dean: "They put freaking make up on us! Those bastards!"
- Sam: "You're Jensen Ackles and I'm something called a 'Jared Padalecki'."
Dean: "So what? Now you're Polish?"
- Dean: "I feel sick. I'm gonna be sick. I feel like this whole place is bad touching me."
- Dean: "The name's Misha. Misha? Misha, Jensen? What's up with the names around here?"
Misha: "You guys, you really punk'd me!"
Misha (tweeting): "Hola mishamigos. J squared got me good. Really starting to feel like one of the guys."
- Dean: "Look at these male modelin' sons of bitches."
Sam: "Hey, apparently it's our job."
- Sam: "It says you're from Texas."
Sam: "And... uh you were on a soap opera."
- Sam: "Wow, I must be the star of this thing."
Dean: "Yeah right."
- Sam: "What am I? Dracula?"
Dean: (revealing a tanning bed) "George Hamilton Dracula."
- Dean: "Dude, you have a camel in your backyard."
Genevieve: "It's an alpaca, dumbass."
- Bob Singer (the director): "What's happening? What's happening?! What's happening!?"
The writer: "An atrocity is happening."
- Sam: "Who wrote this? Nobody says penultimate!"
- Dean: (Gesturing) "Gun...mouth...now."
- Homeless guy: "The scary man killed the attractive crying man..."
- Bob Singer: "You can't come to work on poppers and smuggle kidneys in from Mexico and make up your own lines as you go. You cannot make up your own lines!
- Sam: "At least we're talking."