- Patrick Star
- SpongeBob SquarePants
- Barnacle Boy
- Mermaid Man
- Man Ray
- Incidental 48 (with hair)
- Robot Mantis (debut)
- Realistic Fish Head
- Dirty Bubble
- Jumbo Shrimp
- Atomic Flounder
- Sinister Slug
- Phone operator (heard only)
- Elastic Waistband
- Professor Magma
- Miss Appear
- Pyrite Panderer (debut)
- Hand creature (single appearance)
- Stephen Hillenburg (name written)
- Paul Tibbitt (name written)
- Dina Buteyn (name written)
- Jennie Monica Hammond (name written)
- Peter Bennett (name written)
- King Neptune (mentioned)
- Alan Smart (name written)
- Steven Banks (name written)
- Derek Iversen (name written)
- Mr. Lawrence (name written)
- Dani Michaeli (name written)
- Richard Pursel (name written)
In the beginning of the episode, SpongeBob visits Patrick Star's house and tells him what he got in the mail which was a video of the lost episode of Mermaid Man and Barnacle Boy. They begin watching the video. It begins with the Mermaid Man theme song.
After the narrator announces the name of the episode, (The Secret Meeting) it shows Mermaid Man and Barnacle Boy spying on the Dirty Bubble. He is taking a bus to Bikini Bottom. The two heroes decide to stop whatever evil he is doing. Then, the scene cuts to the Dirty Bubble coming out of the bus, laughing, and Mermaid Man and Barnacle Boy watching. Then, Man Ray, Jumbo Shrimp, Atomic Flounder, and Sinister Slug join the Dirty Bubble. Mermaid Man and Barnacle Boy are worried at this team up. The Dirty Bubble welcomes the villains to the B.G.A.T.F.B.C., which shall be held at the Evil Hotel, April 3, at noon.
Patrick's television becomes filled with static. Patrick yells angrily and SpongeBob quickly repairs the tape. They start watching again. Mermaid Man and Barnacle Boy discuss what to do. Mermaid Man acknowledges that they are out-manned, but they are one step ahead of the villains. He takes a shell and uses it as a phone. He asks for the 'Ocean's greatest heroes' and is told to hold.
The narrator then says "Meanwhile, outside motel Evil," and the scene shows the villains gathering around the building. They enter the building to find two men in white coats sitting at a long table reserved for the villains. The Dirty Bubble says the two men have to leave. One man, who is really Mermaid Man says he thought it was set aside for the I.J.L.S.A. The Dirty Bubble demands to know what it is, and Mermaid takes off the white coat, revealing who he is. The villains are surprised. Mermaid Man introduces the villains to the I.J.L.S.A. First, the Elastic Waistband is seen, then Professor Magma, followed by Miss Appear, and the Pyrite Panderer. They begin to battle. Barnacle Boy is touched by the Atomic Flounder, and grows an evil arm, and is knocked out. The Dirty Bubble shoots Man Ray out of his mouth and fires at the Elastic Waistband, who blocks it with his stretching belly. Mermaid Man jumps to the Evil Arm on Barnacle Boy, who taunts him. The Evil Arm forces Barnacle Boy to swing fists at Mermaid Man. The Elastic Waistband asks what they should do, and Mermaid Man jumps and swings on a chandelier and spins several times in mid-air. He jumps on Barnacle Boy's shoulder and starts wrestling with the Arm. It continues to taunt Mermaid Man, and he pulls Barnacle Boy past Professor Magma, using him as a shield, and attacks the Atomic Flounder, who collapses. The Sinister Slug is seen crawling up a wall behind Mermaid Man and SpongeBob screams to him "Look out, Mermaid Man!" The Slug spits at Mermaid Man. He jumps out of the way and the glop lands on the Atomic Flounder. SpongeBob and Patrick are happy. The slime from the Sinister Slug hardens and Mermaid Man makes the Evil Arm touch the Atomic Flounder. It explodes and Barnacle Boy wakes up. Mermaid Man then uses the hairnet on the Pyrite Panderer as a net and gathers the villains in the hairnet. Mermaid Man demands to know what their group villains' name is, which turns out to be the Bad Guys All Together for Book Club. The Villains sneer, saying they can't arrest them for reading. Mermaid Man confirms this, and tells the audience that no one can arrest you for reading. The show ends and the end credits begin to show.
Patrick thinks the end credits are squiggles and asks him why they are on the screen. SpongeBob explains end credits, and Patrick and SpongeBob thank Neptune for the rewind button, and SpongeBob presses it and the lost episode starts again, as the episode ends.
|( ‣ ) Production music|
|( • ) Original music|
|( ◦ ) SpongeBob music|
• Mermaid Man and Barnacle Boy Action Theme - Michael Bolger, Nicolas Carr, Pat Irwin [Title card]
‣ Marching to Honolulu - Kapono Beamer ["Patrick, guess what came in the mail today!"]
◦ Mermaidman and Barnacle Boy TV Theme - Zeus Cervas, Eban Schletter [Mermaid Man and Barnacle Boy Theme Song]
• Sneaky Buns - Nicolas Carr [The Mer-Cave]
• Mermaid Man and Barnacle Boy Action Theme - Michael Bolger, Nicolas Carr, Pat Irwin ["What's he doing at the bus stop?"]
• Mermaid Man Sting - Nicolas Carr [Transition]
‣ Ramblin' Man from Gramblin' - Sam Spence [villains teaming up]
‣ Heavy Fight - Gerhard Trede ["It's worse than I could have imagined."]
• Noodly Shenanigans - Nicolas Carr, Barry Anthony [SpongeBob fixing the tape]
• Mermaid Man and Barnacle Boy Action Theme - Michael Bolger, Nicolas Carr, Pat Irwin ["Griping guppies, Mermaid Man, we gotta do something!"]
• Mermaid Man Sting - Nicolas Carr [Transition]
‣ Shadow Villain - Meyer Kupferman [at Hotel Evil]
• Mermaid Man and Barnacle Boy Action Theme - Michael Bolger, Nicolas Carr, Pat Irwin [IJLSA introduced]
‣ Crime and Danger Sign #3 - Delle Haensch, Hans Conzelmann [fight scene]
• Mermaid Man and Barnacle Boy Action Theme - Michael Bolger, Nicolas Carr, Pat Irwin ["The Sinister Slug's slime has you stationary and stiff."]
• Mermaid Man Sting - Nicolas Carr [Transition]
‣ International Law - Peter Yorke [book club]
• Mermaid Man and Barnacle Boy Action Theme - Michael Bolger, Nicolas Carr, Pat Irwin [end credits]
◦ Mermaidman and Barnacle Boy TV Theme - Eban Schletter [ending]
- This episode is available on the Heroes of Bikini Bottom, Back to the Past DVD, SpongeBob SquarePants Vol. 11, The Best 200 Episodes Ever, The SpongeBob SquarePants Collection, 3 DVD Value Pack, The SpongeBob SquarePants 8 Season DVD Collection, The Best of Bikini Bottom, Easter with SpongeBob, Big Hits: Volume 2, Triple Pack 3, Kids Double Pack: Volume 2, Kids Double Pack: Volume 3, Complete Seventh Season, and Next 100 Episodes DVDs.
- The International Justice League of Super Acquaintances looks much different from the one in "Mermaid Man and Barnacle Boy V."
- Captain Magma refers to Professor Magma (Ironically) and is just a pile of lava made from coffee.
- Miss Appear looks similar to Wonder Woman and with color changes.
- The Elastic Waistband has the power to puff up instead of super stretch and in a different costume.
- The Quickster has also been replaced by "the Pyrite Panderer."
- Also, Mermaid Man refers to the IJLSA as the International Justice Lodge of Super Acquaintances, instead of saying "League."
- Miss Appear and Elastic Waistband only spoke one line in this episode.
- This is the first episode to be less than 11 minutes since "Pat No Pay" in season 5.
- Mermaid Man and Barnacle Boy's younger selves are voiced by Ernest Borgnine and Tim Conway, who normally voiced their Elderly versions. Previously, the younger versions of the heroes were voiced by Adam West and Burt Ward.
- Fourth Wall Break: The end credits on the video look just like the credits for the show.
- The end credits are actually for the sister episode, "Back to the Past."
- The Atomic Flounder and Jumbo Shrimp both look different than they do in the episode "Mermaid Man and Barnacle Boy II." In addition, unlike in the previous episode, the Atomic Flounder's incarnation this time looks more like a shark and looks nothing like a real-life flounder.
- Man Ray's ray gun has the same design as Plankton's Death Ray.
- This is the second episode in which not one of the ten main characters plays a major role. The first one was "Ugh."
- When Patrick gets worried about the end credits of the show rolling, this references a similar skit to it from the NickToons Summer Splash back in 2000 when Patrick didn't want Rugrats (the show whose credits were rolling at the time) to end.
- This was the last usage of the track "Marching to Honolulu" until "Old Man Patrick."
- The title card background is also similar to "Mermaid Man vs. SpongeBob," except this one is red and yellow instead of orange and blue.
- When SpongeBob and Patrick say, "Yay!," SpongeBob's eyelashes briefly go missing after he blinks.
- When Mermaid Man is flipping, talking about the plan on how he could get Barnacle Boy back, his mouth never moves.
- When SpongeBob is rewinding the tape, he actually pressed the "Eject" button.
- While Mermaid Man contacts the other heroes, the narrator says 'Meanwhile' and shows the Book Club beginning. However, the meeting was supposed to take place the next day.
- The name of the building in which the book club meets is inconsistent throughout the episode. On the invitation cards, it is "The Evil Hotel." The narrator later says, "Hotel Evil." The sign on the actual building reads, "Motel Evil."
- ^ https://www.youtube.com/watch?v=XAuxaquWmzk
- ^ https://web.archive.org/web/20170817053052/http://www.throng.co.nz/tag/spongebob-squarepants/
- ^ https://cocatalog.loc.gov/cgi-bin/Pwebrecon.cgi?v1=317&ti=301,317&Search%5FArg=Spongebob%20SquarePants&Search%5FCode=FT%2A&CNT=25&REC=0&RD=0&RC=0&PID=dHJUy5Ig3odNV0wYMchIV9BPt2xvN&SEQ=20220519194853&SID=1