- SpongeBob SquarePants
- Off Model SpongeBob (debut)
- Squidward Tentacles (cameo)
- Gnarly Squid (debut)
- Eugene H. Krabs
- Sheldon J. Plankton
- Ideal Plankton (debut)
- Karen Plankton
- Virus (debut)
- Female hick (debut)
- Hanna (debut)
- Robot SpongeBob (cameo)
- Plankton's cousins (cameo)
- Old Man Jenkins (cameo)
- Lily Plankton (cameo)
- King Neptune (mentioned)
- Incidental 69
- Incidental 68
- Nat Peterson
- Incidental 67
The episode starts with Karen having lunch with her friend, Hanna. She sneezes on Karen and tells her to go home and reboot. Afterwards, Karen gets a virus in her system after Hanna spreads her bug on her databanks. Plankton then sees SpongeBob outside the Chum Bucket, banging a hammer that's on his head on the door. Plankton tells SpongeBob that Karen needs help, so SpongeBob tries to come up with names for the mission he is going to do. He decides to name it Operation: Save Karen. Plankton then inserts SpongeBob into Karen's hard drive.
When SpongeBob is downloaded, Plankton tasks him to look for any destruction and follow it to the virus. Karen gets up from her laying table and gets out of the Chum Bucket, and invades the Krusty Krab. Plankton gets shocked by this and goes toward the scene. SpongeBob, inside Karen, sees the destruction of the virus, and Plankton tells him if he doesn't destroy it soon, it will fry Karen's Memory Bank. Mr. Krabs says Plankton needs to control his wife, as she's destroying the Krusty Krab.
SpongeBob, walking through Karen's insides, accidentally switches a button that turns on a ton of lasers, but just before he gets shot, someone with a muscular body saves him. He, who is revealed to be Karen's version of Plankton, says they'd better be going, by showing SpongeBob that the virus is eating stuff from Karen's hard drive. The two then climb a wall and then see Karen's version of Mr. Krabs, Squidward, and SpongeBob. However, they think Ideal Plankton and SpongeBob are intruders, so they try to eliminate them. Ideal Plankton defeats Squidward easily, but SpongeBob and Ideal SpongeBob hit each and both look like Karen's version. Ideal Plankton doesn't know which is which, but luckily, he shoots the evil one. The two then see the virus, who is heading for Karen's memory banks.
Ideal Plankton gives SpongeBob a rope to go over the gap between them and the memory banks. When Ideal Plankton tries to swing, he accidentally falls off into the void. However, he still encourages SpongeBob to go and save Karen. Meanwhile, Plankton is in the car with a crazy Karen, who drives to the Wagon Wheel with a bunch of other people and starts to party. Plankton reminds SpongeBob that Karen is completely melting down and that he'd better do something quick. SpongeBob meanwhile has reached the memory banks of Karen. He sees that the virus has been eating memories Karen had. SpongeBob tells the virus to stop, but the virus instead tries to attack SpongeBob, who dodges its attack. The virus becomes a dragon and breathes fire on SpongeBob.
SpongeBob runs until he reaches the end of Karen's memories. SpongeBob tells Plankton Karen needs to create more memories so he can have more space to run. Plankton asks SpongeBob if he running after Karen is enough of a memory, but SpongeBob says no. The virus then comes and SpongeBob falls to pieces. When SpongeBob comes back together, he gets one extra piece. He throws it onto the ground and the virus eats it. SpongeBob then realizes that the virus is eating Karen's memories because he's hungry. SpongeBob then gets out of a warned out Karen, and puts the virus on a Krabby Patty so it'll take 300 years for it to chew through it. Karen starts to turn back to normal and sees Plankton in her form. Plankton is glad that Karen is back to normal, although Karen thinks she's still delirious in a good way.
|( ‣ ) Associated production music|
|( • ) Original music|
|( ◦ ) SpongeBob music|
‣ Happy Links 6-9 - Paul Fenoulhet [Karen and Hanna at the Chum Bucket]
‣ Happy Links 1-5 - Paul Fenoulhet [Karen sneezes at Plankton]
‣ Oh My Trill! - [ProjectSAM Symphobia Colours: Animator] [Karen starts malfunctioning]
‣ Uh Oh Flutter-Eyed - [ProjectSAM Symphobia Colours: Animator] [Karen crashes into a wall]
• Hot Steel and Slide Licks (i) - Jeremy Wakefield ["Uh-oh. My ones and zeroes look like 10, 10, 10, 10."]
‣ Mission Improbable - Nicolas Carr, Barry Anthony ["Someone's gonna have to get inside you and kill that virus."]
‣ Gator - Steve Belfer [SpongeBob knocking Chum Bucket door with a hammer]
‣ In Disguise Ensemble - [ProjectSAM Symphobia Colours: Animator] [Plankton tells SpongeBob that Karen needs his help]
‣ Phrases - Is It Jazz - [ProjectSAM Symphobia Colours: Animator] ["♪Who lives in a crabapple under a pea♪"]
‣ Lap Steel - Nicolas Carr [Transition to next scene]
‣ Phrases - Is It Jazz - [ProjectSAM Symphobia Colours: Animator] ["♪Observant and yellow fellow is he♪"]
‣ ? ["Journey to the Center of Karen."]
‣ Arnold is Back 2 - Gregor Narholz ["The Mainframe Mission."]
‣ Harp Ding - Nicolas Carr ["Ooh, I know!"]
‣ Glory Road - Sam Fonteyn ["Operation: Save Karen!"]
‣ Toy Piano - Nicolas Carr, Barry Anthony [SpongeBob holds up a drawing]
‣ Hot Steel and Slide Licks - Jeremy Wakefield [Chum Bucket exploded]
‣ Laughter Muted Trumpet - [ProjectSAM Symphobia Colours: Animator] [Plankton blows the fire out on his antennas]
‣ Neutral Mood - Simon May [SpongeBob zapped and injected into Karen]
‣ In Disguise Ensemble - [ProjectSAM Symphobia Colours: Animator] ["Get away."]
‣ Uh Oh Flutter-Eyed - [ProjectSAM Symphobia Colours: Animator] [Plankton gets electrocuted]
‣ Space Trek - Philip Johnston, Norman Whittle [SpongeBob arrives at Karen's hard drive]
‣ Destination Unknown - Gregor Narholz [Plankton starts talking to SpongeBob via megaphone]
‣ Tiptoe Quick Peek - [ProjectSAM Symphobia Colours: Animator] ["Talk to me, you digitized doofus!"]
‣ Tiptoe Footsteps - [ProjectSAM Symphobia Colours: Animator] ["Plankton, I do not respond to insults."]
‣ Destination Unknown - Gregor Narholz [Plankton tells SpongeBob to look for destruction]
‣ Monster Movie Orchestra - Steve Sechi, Kostas Varotsis [SpongeBob falls through a hole made by the virus]
‣ Monster Bug A - Gregor Narholz [Karen gets off the table and starts destroying the Krusty Krab]
‣ Melodramatic Moments - Michael Bolger, Nicolas Carr ["I need you to control your wife. Er, computer, or whatever."]
• Hot Steel and Slide Licks (j) - Jeremy Wakefield [Karen throws Squidward away and climbs into the register boat]
‣ Melodramatic Moments - Michael Bolger, Nicolas Carr [Krabs grabs the cash register out of Karen]
• Hot Steel and Slide Licks (o) - Jeremy Wakefield ["Wow, I can never un-see that."]
‣ Code "Dead End" - Gregor Narholz [SpongeBob wandering through the hard drive]
‣ Odyssey - Sam Spence [Ideal Plankton appears and blasts the lasers with a laser gun]
‣ Comedy Punctuations and Bridges 3 - Fredric Bayco [SpongeBob sighs and skips]
‣ Fun of the Fair - David Farnon [Amusement park in Karen's hard drive]
‣ Musique De L'Infini - Jean-Jacques Perrey [Virus destroys Karen's anger control center and love center]
‣ Odyssey - Sam Spence [Ideal Plankton climbs up a wall with SpongeBob]
‣ Unknown Track 72 - Money Krabs appears
‣ ? [Gnarly Squid appears]
• Hot Steel and Slide Licks (f) - Jeremy Wakefield ["Hmm? Uh, nothing like a little make-up couldn't fix."]
‣ ? [Off Model SpongeBob appears]
‣ Armed Attack - Jean Clero [Ideal Plankton fights Money Krabs and Gnarly Squid]
‣ ? [Both SpongeBobs babbling]
‣ Code "Dead End" - Gregor Narholz ["Neptune's network! Which one of you is the real SpongeBob?"]
‣ Unknown Track 72 - SpongeBob claps
‣ Musique De L'Infini - Jean-Jacques Perrey [Virus roars to SpongeBob and Ideal Plankton]
‣ Thrill Ride - Gregor Narholz [SpongeBob swings across a ravine]
‣ Tower of Evil - Magnum Opus [Ideal Plankton falls into the ravine]
‣ Odyssey - Sam Spence ["I mean, yes!"]
‣ Hawaiian Adventures SpongeBob Theme - Nicolas Carr, Sage Guyton, Jeremy Wakefield [Karen driving crazily a boat with Plankton]
‣ Unknown Track 60 - Nicolas Carr, Sage Guyton, Jeremy Wakefield [Karen crashes the boat into Wagon Wheel]
‣ On Fire - Gregor Narholz [Virus at Karen's memory bank/SpongeBob escapes from virus until he bumps into a brick wall]
‣ Vibe Sting - Nicolas Carr ["I always wind up with one extra piece."]
‣ One Zero Zero - Harry Breuer, Jean-Jacques Perrey [Virus eats SpongeBob's extra piece]
• Hot Steel and Slide Licks (p) - Jeremy Wakefield [Karen is tired and shuts off]
‣ Earl's Revenge - Sage Guyton, Jeremy Wakefield [Ending]
- This is the second SpongeBob SquarePants production that involves CGI, in this episode, it's inside Karen. The first production is The SpongeBob Movie: Sponge Out of Water.
- This and "Girls' Night Out" are the first episodes to premiere on a day that daylight saving time ends in the United States.
- This episode premiered in the Netherlands on October 27, 2018, eight days prior to its premiere in the United States.
- When this episode premiered, it was paired up with "Girls' Night Out."
- This episode premiered 13 years after "SquidBob TentaclePants," and premiered a year after "Spin the Bottle" and "There's a Sponge in My Soup" premiered in France, and "The Incredible Shrinking Sponge" and "Sportz?" premiered in the Netherlands.
- This is among the many episodes to have an animated title card.
- Karen sings a warped version of the SpongeBob SquarePants theme song in her delusional state.
- This episode was originally going to premiere on October 24, 2018, before the new president of Nickelodeon signed on, at which it was moved to November 4, 2018.
- When SpongeBob gets mixed up after he is charred by the virus, he resembles how he does at one point in the theme song sequence.
- The flashbacks in Karen's memory includes footage from "Plankton!," "Welcome to the Chum Bucket," "The Algae's Always Greener," "Plankton's Army," "Enemy In-Law," "Komputer Overload," "Salsa Imbecilicus," "Plankton Gets the Boot," and "F.U.N."
- This marks the first usage of the APM track "On Fire" since "Banned in Bikini Bottom" and "Arnold is Back 2" since "Patty Hype."
- SpongeBob's karate gear makes its first appearance since "Sandy's Nutmare."
- When Karen throws the car, it knocks off one of flower's in the sky
- Ideal Plankton is a reference to Superman.
- Coincidentally, the virus is voiced by Clancy Brown, the voice of Lex Luthor in the DC Animated Universe.
- "Journey to the Center of Karen" is a reference to Journey to the Center of the Earth.