(+ character appears outside of the story).
- Patchy the Pirate+ (original airing only)
- Potty the Parrot+ (original airing only)
- SpongeBob SquarePants+
- Frankie Billy
- Squidward Tentacles
- Nat Peterson (2 cameos)
- Patrick Star+
- Eugene H. Krabs
- King Neptune (mentioned)
- Two kids (debut)
- Sheldon J. Plankton
- Old Man Jenkins
- Norma Rechid
- Martha Smith
- Officer Rob Johnson
- Nathiel Waters
- Jimmy Gus
- Jennifer Millie
- Fred (blue)
- Tina Fran
- Miss Shell
- Abigail Marge
One day in Bikini Bottom, SpongeBob wipes the grill with a sponge (made from part of his own tongue) at the Krusty Krab. He proclaims that it is freshly clean and tries to convince a customer to eat a Krabby Patty that was on the grill. When SpongeBob goes back inside to cook the patty, the customer asks Squidward why he does not want a Krabby Patty, and he replies that he has seen what SpongeBob cleans the grill with. It goes back to SpongeBob, who is on his way to the freezer for a patty when he slips on a puddle of water. Upon closer inspection, SpongeBob observes that the puddle is coming from the sink, which is clogged with water. As he is trying to figure out how to unclog the drain, Patrick comes in and slips as well. He helps SpongeBob try to pull the drain plug.Eventually, Mr. Krabs overhears them trying to pull the drain plug and stops them before they have a chance. He tells them the story of the Main Drain. He tells them that there was a plug that two kids apparently pulled long ago that ended the world of Bikini Bottom. When they ask him where it is, he becomes nervous and tells them to go away. The two go outside and SpongeBob accidentally steps on Plankton. He peels him off his shoe and then they ask him about it. He becomes nervous as well and tells them to go away. SpongeBob says that he heard it from Mr. Krabs, and Plankton claims Mr. Krabs was lying. They ask him where it is they once again do not get the answer. They turn to Old Man Jenkins, but he yields no results.
They then go on an adventure to find the plug by dragging Patrick's house around. Just before they pull the plug, Mr. Krabs and Plankton stop them and tell the story of how they were the ones that pulled the plug when they were younger. They explain that they lied because they did not want SpongeBob and Patrick to look for it. Unfortunately, Patrick had already pulled the plug when they were telling the story and everything (including themselves and the Bikini Bottomites) is sucked into the drain.
Patrick then sits up in his bed, telling SpongeBob that everything was "the most realistic story he has ever heard," indicating everything that happened was only SpongeBob's story.
|( ‣ ) Associated production music|
|( • ) Original music|
|( ◦ ) SpongeBob music|
‣ Sailor's Sting 12 - Michael Bolger, Nicolas Carr [SpongeBob exits the freezer]
‣ Sailor's Sting 7 - Michael Bolger, Nicolas Carr [SpongeBob cleaning the grill]
‣ Dramatic Bridge 4 - Phil Green [SpongeBob slipping]
‣ Vibe Q Sting - Nicolas Carr ["Hey, where'd all this water come from?"]
‣ Clumsy C - Bernd Gesell [sink clogged]
‣ Killer Birds [#36] - Gregor F. Narholz ["Pull the drain plug."]
‣ Steel Sting (b) - Jeremy Wakefield ["What in Neptune's bathtub do you think you're doing, lad?"]
‣ Unknown Track 34 - Nicolas Carr ["Hmm... One sec."]
‣ Agitation Bridge 3 - Phil Green ["...of the Main Drain."/"It happened a long time ago..."]
‣ Zoom D - Dick De Benedictis ["...putting them under its spell."]
‣ Domestic Fun (a) - Ernest Tomlinson [kids wandering through the ocean]
‣ Domestic Fun (b) - Ernest Tomlinson [they pull the drain plug]
‣ Epic Adventure - Dick Stephen Walter [kids sucked down the drain]
‣ Dramatic Encounter - Gregor F. Narholz ["And nobody was ever heard from again."]
‣ Steel Sting (c) - Jeremy Wakefield ["I don't know where it is!"]
‣ Goofy Conversation - Nicolas Carr, Barry Anthony ["Mr. Krabs sure has a lot of baggage about drain dealies."]
‣ Drama Link (g) - Hubert Clifford ["The main drain?"]
‣ Comic Walk - Nicolas Carr [Plankton says there is no main drain]
‣ Down in Davy Jones' Locker - Nicolas Carr ["Why on earth would Krabs tell those two blunderers about the main drain?"]
‣ Befuddled Gent - Phil Green ["Old Man Jenkins!"]
‣ Steel Sting - Jeremy Wakefield ["I have no idea."]
‣ Bucaneers [#91] - Harry Bluestone, Emil Cadkin ["Patrick, we need to find that drain!"]
‣ Shock - Cornelus Joh Bolten [Patrick thinking]
‣ Steel Sting (o) - Jeremy Wakefield [Patrick babbling]
‣ Gator - Steve Belfer [SpongeBob blowing bubbles]
‣ Variety Link (d) - Dick Stephen Walter [bus-shaped bubble]
‣ Editor's Falling Over (b) - Dick Stephen Walter [bubble pops]
‣ Harp Ding - Nicolas Carr ["I know!"]
‣ Steel Licks (a) - Jeremy Wakefield [SpongeBob blows a bubble]
‣ Skipping to School - Sage Guyton, Jeremy Wakefield [Patrick's house floating up]
‣ Drama Link (d) - Hubert Clifford [SpongeBob and Patrick scream]
‣ Steel Sting (l) - Jeremy Wakefield ["Another miserable day..."]
‣ Steel Sting (s) - Jeremy Wakefield ["Oh, how are we gonna find the center of the ocean now?"]
‣ Harp Ding - Nicolas Carr [Patrick gets an idea]
‣ The Jovial Buccaneers [#32] - John Fox [Patrick pulling his house]
‣ Hide and Seek [#17] - Harry Bluestone, Emil Cadkin [they find the drain]
‣ Finger of Fear - Fredric Bayco ["Why would we do that?"]
‣ Dramatic Impact 3 - Ivor Slaney ["NO!"]
‣ Dramatic Impact 2 - Ivor Slaney [SpongeBob and Patrick gasp]
‣ Domestic Fun (a) - Ernest Tomlinson [flashback to Krabs and Plankton as kids]
‣ Epic Adventure - Dick Stephen Walter [everything sucked down the drain]
‣ Steel Licks (d) - Jeremy Wakefield ["We had to lie to keep you from looking for it."]
‣ Dramatic Impact 6 - Ivor Slaney [Patrick pulls the drain plug]
‣ Epic Adventure - Dick Stephen Walter [everything sucked down the drain]
‣ Steel Sting (b) - Jeremy Wakefield [ending]
- This episode is available on the Legends of Bikini Bottom, Complete Seventh Season, and Next 100 Episodes DVDs.
- As of August 19, 2016, The Internet Movie Database (IMDB) gives this episode a rating of 7.5/10 based on 26 ratings by users. TV.com users give this episode a rating of 7.9/10 based on 123 votes.
- Although this episode premiered in 2011, it was made in 2010 according to the credits.
- The title card letters are similar to "The Fish Bowl."
- This is the only episode in the "Legends Of Bikini Bottom" series that doesn't have a strange character (not counting Old Man Jenkins, who has a minor role).
- Though it was revealed that this episode was only a story being read to Patrick by SpongeBob, the entire population of Bikini Bottom was sucked away before: in the episode "A Flea in Her Dome," everyone was sucked into Sandy's treedome. This event could have been the inspiration for this story.
- The Main Drain, which sucks in all of Bikini Bottom, obviously refers to the end-of-the-world scenario "killer strangelet."
- Like his arms and legs, SpongeBob's tongue can also be detached and reattached.
- It's odd with Plankton's antenna, in some episodes, it breaks quite easily, such as "Christmas Who?" with a bauble, but it can hold bubbles and a heavy rock with Patrick and SpongeBob on it.
- This is the second time Mr. Krabs and Plankton were shown as friends and kids. The first was "Friend or Foe."
- On the Legends of Bikini Bottom DVD cover, some of the stories are being sucked down into the main drain, such as "The Monster Who Came to Bikini Bottom," "Welcome to the Bikini Bottom Triangle," "The Curse of the Hex," and "Trenchbillies."
- This is the third episode where Mr. Krabs warns SpongeBob and Patrick about doing something, but they do not listen to him. The first being "Hooky," second being "Sailor Mouth," and the fourth being "Face Freeze!."
- This episode reveals that SpongeBob is aware that Squidward thinks his life sucks as he added a scene where Squidward says, "Another miserable day..." in his story.
- This episode premiered eight years after the release of Tales from the Deep, Bikini Bottom Bash!, and Deep Sea Sillies and six years after The SpongeBob SquarePants Movie was released in Spain.
- A storyboard image appears on the special, Behind the Scenes: Legends of Bikini Bottom.
- It was revealed in this episode when SpongeBob and Patrick are seen flying on Patrick's house intended with bubble made balloons. This scene of Patrick's house is very similar to Carl Fredricksen's house from the Disney/Pixar film Up.
- When SpongeBob said, "Patrick we need to find that drain," the road suddenly disappears.
- When SpongeBob put the danger sign on the floor, the lever beside the freezer disappears.
- When Mr. Krabs turned off the lights, it is the left side, but when he finished the story, the switch suddenly changed positions. The next scene shows that the switch is above SpongeBob, hanging on the ceiling.
- Patrick turning on music on his radio when Mr. Krabs is about to tell the story of the Main Drain.