- French narrator
- Eugene H. Krabs
- SpongeBob SquarePants
- Squidward Tentacles
- Sheldon J. Plankton
- Plankton's robot (debut)
- Karen Plankton
- Bar customers
- Plankton's imaginary family (debut)
- Plankton's cousins (debut)
At the Krusty Krab, Mr. Krabs announces that it is the 25th anniversary of the first time Plankton attempted to steal his secret recipe and explains all his failed attempts. Suddenly, a robot enters the restaurant, and Mr. Krabs tells SpongeBob to clean out the men's bathroom and pushes Squidward aside, saying that he will handle this customer. However, the robot orders chili coral bits instead of a Krabby Patty, it pays for them and leaves. Mr. Krabs is surprised that the robot was not Plankton, but Plankton then suddenly jumps out of the dollar bill the robot gave him. However, Plankton hadn't planned what to do next, not thinking he'd ever get this far... He is simply flushed down the toilet by Mr. Krabs, screaming as he gets sucked down to the sewer.
He returns to the Chum Bucket, preferring not to talk about the failure. Karen shows clips of him being squished by Mr. Krabs, and more recently being flushed down the toilet, saying that he fails because he doesn't talk. She then suggests hiring some henchmen to help him. He first goes to the Salty Spittoon, but the thugs prefer to smash him. Plankton sulks that anything he does, he just get's stepped on by people. He then realizes that he has thousands of inbred relatives across the sea, and invites them all to come to the Chum Bucket, thinking they will all be evil geniuses like himself. However, when they arrive, he finds out they are all inbred rednecks, and comments that he's "been away from home longer than (he) thought."
He calls them to a meeting and gets them to agree to his plan in exchange for root beer. Plankton's first name is revealed to be Sheldon, which Karen finds hysterical and mocks his name. Plankton's army then attacks the Krusty Krab, tying up Mr. Krabs and Squidward in a toilet. The Planktons open the safe containing the Krabby Patty secret recipe. Before Plankton reads the recipe, Mr. Krabs pleads him not to read it, saying "There some things this world weren't meant to be seen by mortal eyes!" Plankton reads it anyway. The ingredients turn out to be:
- A pinch of salt
- 3 tsp. of chopped onions
- A cup of love
- 4 lb of freshly ground Plankton
Mr. Krabs says he warned him. Plankton is horrified by this, and runs away. The other planktons read it and run (except for Clem, who can't read, but Mr. Krabs orders him to get out). Mr. Krabs and Squidward manage to escape from the toilet, and SpongeBob returns from his task, and asks what happened. Squidward asks if a Krabby Patty is actually made of plankton, Mr. Krabs explains that the recipe that Plankton read is fake,
and the real one is hidden somewhere "No one, not even Plankton, would ever figure out." Squidward then correctly guesses that it is under Mr. Krabs' mattress, and Mr. Krabs runs to his house, yelling "Curse you, Squidward!"
|( ‣ ) Associated production music|
|( • ) Original music|
|( ◦ ) SpongeBob music|
‣ Zelle 506 - Gerhard Trede [title card]
‣ Keel Row - Brian Peters [opening]
‣ Premonition of Disaster - Arthur Harold Wilkinson [robot customer enters]
‣ Tomfoolery - David Snell [robot orders chili coral bits]
‣ Six Powerful Cues (a) - Wilfred William Burns [Plankton jumps out of dollar bill]
‣ Drunken Sailor (b) - Robin Jeffrey, Tim Laycock [Plankton flushed down toilet]
‣ Al Capone Blues - Eric Gemsa [Plankton goes home]
‣ Vibe Sting - Nicolas Carr ["Henchmen?"]
‣ Zelle 501 - Gerhard Trede ["I'll canvass all the seediest lowbrow dives in town to find my minions!"]
‣ Rock Monster (a) - Wolfgang Killian, Hermann Langschwert [tough guys playing pool]
‣ Drowsy Reef - Jeremy Wakefield, Sage Guyton [Plankton in a wheelchair]
‣ Harp Ding - Nicolas Carr ["Wait... that's it!"]
‣ Jerry Cotton - Gerhard Trede [Plankton gathering family members]
‣ Let's Dance Susanna - Roy Henley [they're all hillbillies]
‣ Wooden Bear - Gil Flat, Tony Tape, Florian Voelxen [Plankton introduces them to Karen]
‣ Buffalo Girls - Martyn Laight ["What's in it for us?"]
‣ Zelle 503 - Gerhard Trede ["Root beer?!"]
‣ Zelle 506 - Gerhard Trede ["I have the restaurant surrounded."]
‣ Hog Fever (a) - Graham D.H. Preskett [plankton invade Krusty Krab]
‣ Kommissar X - Gerhard Trede [Krabs in toilet]
‣ The Oracle - David Farnon [safe opened]
‣ Journey to the Magic Island - Gregor F. Narholz [Plankton removes formula from bottle]
‣ Apalachian Banjo Duel - Larry Hochman ["And of course I had a little help from the family."]
‣ Dramatic Climax - Mike Sunderland [Krabs warns Plankton not to look at the formula]
‣ Against the Law (e) - Wilfred William Burns [Plankton reading the formula]
‣ Hawaiian Adventures SpongeBob Theme - Sage Guyton, Jeremy Wakefield [Plankton runs away]
‣ Let's Dance Susanna - Roy Henley ["Get outta here!"]
‣ The Tip Top Polka/The Cliff Polka - Chelmsford Folk Band [Krabs says it wasn't the real formula]
‣ Hawaiian Adventures SpongeBob Theme - Sage Guyton, Jeremy Wakefield [ending]
- This episode is available on the SpongeBob Goes Prehistoric, Absorbing Favorites, Complete 3rd Season, First 100 Episodes DVDs.
- "Plankton's Army" was ranked #66 during the Best Day Ever event on November 9–10, 2006.
- This was Jay Lender and Sam Henderson's final episode as writers and storyboard directors.
- This episode aired in Germany on September 24, 2003, before it aired in the United States.
- When it originally aired in the USA, this episode was shown before "Missing Identity" due to being advertised as a "special" episode.
- Before it aired, many people mistook this episode to be a special or even a movie due to the nature of its advertisements.
- SpongeBob only appears in two scenes: one at the very beginning and the other at the very end. This makes the episode to be one of the smallest appearances of SpongeBob in an episode ever to be aired, similar to "New Leaf," "Rise and Shine," and "Mall Girl Pearl."
- Plankton's past attempts at stealing the formula shown in this episode include:
- Asking nicely; Mr. Krabs said no.
- Wearing a cockroach costume; Mr. Krabs stepped on him.
- Drinking a potion that turned him into a cockroach; Mr. Krabs stepped on him.
- Protesting to Krabs that he is not a cockroach on a picket sign ("civil disobedience"); Krabs stepped on him again.
- One line from this episode can be heard sped up in "Krusty Krab Training Video."
- This episode is one of the rare occasions where Plankton is squashed by his wife, Karen (under her robotic hand).
- Plankton says that "United, the Plankton family could be a real pain in the fanny!" However, on SpongeBob Goes Prehistoric, Absorbing Favorites, and The Complete 3rd Season DVDs, the closed captions say "belly" instead of "fanny." Although, this error is fixed in the closed captioning on The First 100 Episodes DVD.
- According to the phone book:
- There are five "S. Plankton"s.
- At maximum, there is one "M. Plankton."
- There are 15 or 16 "N. Plankton"s.
- There are 15 "O. Plankton"s and "P. Plankton"s each.
- It should be noted that when Plankton was talking about how many other Planktons Mr. Krabs could handle, he was saying the number used in the power of ten in scientific notation.
- Plankton's family shows much resemblance to the Trenchbillies because of their lifestyle and appearance.
- Running Gag: Karen showing "SHELDON" on her screen as Plankton is trying to talk.
- It is revealed that Plankton's full name is "Sheldon J. Plankton."
- Plankton's snare drumroll that he performed sounded exactly the same as the drumroll in episodes such as "Wet Painters" and "The Fry Cook Games."
- It turns out that Mr. Krabs hides the Krabby Patty secret formula in his mattress just like how he hides his money.
- Instead of saying he can't read, Clem said "For what?" in Indonesia. There were also few other lines that had been edited aside that one:
- The line "You planted grass?" was changed to "You came to destroy us?" This resulting Plankton's line to respond it changed from "Grass?!?" to "Destroy?!?"
- The line "Hot dog!" was changed to "Yes! Very nice!"
- The line "I'm telling you, you won't be able to handle the truth. There are some things in this world that weren't meant for mortal eyes." changed to "I'm telling you. I mean it! There are purple print that you won't able to comprehend!"
- For unknown reasons, some television guides say the episode premiered in 2002 when it actually was premiered in 2004. This mistake may be because the episode is copyrighted in the year 2002, but not aired on American TV until 2004. Dish Networks original broadcast also set the episode to be aired in 2002 but changed to its correct date.
- This episode wasn't listed in Comcast cable guides; only "Missing Identity" was.
- This error was fixed at some point.
- When Plankton had broken body parts, he appeared to have similar broken body parts to a disassembled Mr. Potatohead.
- It's possible that this episode is a reference to United Plankton Pictures, Inc. as its logo shows several planktons holding "hands."
- The name of Plankton's cousin Billy Billy Bo-Illy Bonana Fanna Fo-Filly is a reference to the song "The Name Game," originally made by Shirley Ellis in 1964.
- The robot who purchases the Coral Bits has a revolving light over its "eyes," much like the Cylons from Battlestar Galactica.
- In this episode, Mr. Krabs claims that Plankton has been trying to steal the formula for 25 years; however, in "Spy Buddies" (which aired three years after this episode), he claims that Plankton has been trying to steal it for 20 years. It's possible that "Spy Buddies" took place before "Plankton's Army."
- When Mr. Krabs said "Today is the 25th anniversary of the first time my arch rival, Plankton, ever tried to steal me secret Krabby Patty formula," the door to Mr. Krabs' office was shown; but when the robot showed up, the door was gone, then when Mr. Krabs and Squidward walked outside, the door was back.
- When the robot shows up at the Krusty Krab, the Chum Bucket across the street is missing.
- When Plankton says "Who will join me!," his mouth is out of sync.
- When Plankton is standing on the phone book, when he says, "or 100," he is next to "S. Plankton," but when he says, "or 1000," he is next to "O. Plankton."
- The phone book does not contain phone numbers.
- Outside the Krusty Krab there are millions of Planktons surrounding the restaurant, but after Plankton retreats to the Chum Bucket, there are fewer of them.
- When Plankton ran from the Krusty Krab back to the Chum Bucket, the road is much more curved and longer than usual.
- When SpongeBob came back after Plankton's cousins ran away, he wasn't wearing his Krusty Krab Employee Hat, but in the next scene, he is.