- Squidward Tentacles
- SpongeBob SquarePants
- Eugene H. Krabs
- Patrick Star
- Mattresses & Then Some employee (debut)
- Pearl Krabs (cameo in picture)
- Dr. Actor (debut)
- Officer Slugfish
- JK (debut)
- Nurse (debut)
- Dr. Sileen (debut)
- Administrator Flotsam (debut)
- Guard worm (debut)
In the beginning of the episode, SpongeBob and Squidward arrive at the Krusty Krab, only to find out it has not opened yet. SpongeBob becomes saddened by this, until a very cranky Mr. Krabs comes after throwing out his back due to his old, lumpy mattress. SpongeBob suggests that he and Squidward buy him a new one, but because he does not want to waste his hard-earned money on his cheapskate boss, Squidward refuses, so Patrick joins SpongeBob in buying a new mattress instead. The two go to a massive mattress emporium, where they buy a comfortable new mattress to replace his old one.
They make a card for him, which Squidward signs, giving himself full credit for the gift. The next night, the trio surprise Mr. Krabs with his new mattress. When Squidward reveals to Mr. Krabs that he had his old mattress thrown away to the dump, Mr. Krabs gets furious at him, revealing that all of his money was in that mattress. He throws a tantrum at Squidward, and asks him where the mattress was. Krabs then goes into a "Cash Coma," and ends up in the hospital, where the doctor explains that only the return of his money can save his life. Squidward insists that it was SpongeBob's fault, but a police officer shows him the card saying, "This was all MY idea, love Squidward.", which states that he is solely responsible. The cop says that if Krabs dies, Squidward will be charged for his death and sent to jail. Squidward begins to threaten to kill SpongeBob, but the police officer stops him from doing so.
Squidward, SpongeBob, and Patrick go to the dump to retrieve the mattress, only to find that there is a vicious guard worm sleeping on top of it.
Meanwhile, the doctor realizes that Mr. Krabs has no insurance and cannot afford his hospital room, so he moves him into the hallway in front of the vending machines.
At the dump, Squidward tells SpongeBob and Patrick to go inside and get the mattress after warning them not to wake the worm, since it will attack. They climb the fence, but they end up becoming distracted by the view, causing an angry Squidward to shake and overturn the fence, accidentally trapping him inside and waking the worm, who promptly mauls him, much to SpongeBob and Patrick's horror.
At the hospital, the doctors "surgically remove" Mr. Krabs from the building and leave him on the sidewalk to get to the "Nutty Nut Bar," a candy bar in the vending machines he is blocking.
Squidward then devises another plan, where SpongeBob and Patrick distract the worm while he retrieves the mattress. The worm becomes obedient to SpongeBob when he sees the wooden spoon he is holding up. SpongeBob unintentionally throws it towards Squidward for the worm to fetch, and Squidward is subsequently attacked by the worm once again.
Back at the hospital, Administrator Flotsam is outraged that Mr. Krabs has been left outside, and they push him down the hill. Next, Squidward has SpongeBob and Patrick dress as "choice cuts" so that the worm will eat them, telling them that they are in Halloween costumes and that when the worm sees them, he will realize that he forgot about Halloween and will leave to go get candy, which is obviously false and meant for the worm to attack them instead of him.
When Squidward expresses his certainty he will be not be hurt this time, Mr. Krabs suddenly rolls into the dump, running over Squidward, and lands on his old mattress, reviving him. He effortlessly throws the worm aside. Mr. Krabs notices SpongeBob and Patrick and growls at them, but they tell him it is them, and Mr. Krabs asks why they are dressed as meat. SpongeBob tells him that they are not just meat, but also choice cuts.
Squidward gives up trying to get the worm to attack them, and the worm then lands in Squidward's arms and begins chasing him out of the dump and down the road Mr. Krabs came from, as the episode ends.
- Mr. Krabs being pushed to different places by the nurse, such as near the vending machines and outside.
- Squidward being attacked by the guard worm.
|( ‣ ) Associated production music|
|( • ) Original music|
|( ◦ ) SpongeBob music|
‣ Hula Festival - George Elliott [title card]
‣ Rule Britannia - Anthony Wakefield [opening]
‣ Dancing the Hula - Kapono Beamer [Squidward going to work]
‣ Torn Apart - Mike Sunderland [Krusty Krab closed]
‣ Broken Romance - Mike Sunderland ["The doors are locked. The doors are locked and we are on the outside. Outsiders."]
‣ Hawaiian Beach - Peter Dennis [Krabs arrives]
‣ Beach Party - Lew Raymond, The White Caps, Harry Bluestone ["It's a new dance craze!"]
• New Dance Craze - Nicolas Carr [Cymbal after "Beach Party"]
‣ Hawaiian Beach - Peter Dennis ["I am hurt, you idiot!"]
• Lap Steel - Nicolas Carr ["You'll warm up to the idea."]
‣ Awakening Memories - Paul Fenoulhet [mattress store]
• Sponge Chase - Nicolas Carr [trying out different mattresses]
‣ Dickhäuter - Gerhard Trede [that night...]
‣ Unknown Track 4 - ? [Krabs gets surprised]
‣ Action Cut A - Gregor F. Narholz ["All my money was in that mattress!"]
‣ Unknown Track 5 - ? [Krabs faints]
‣ Classic Soap 14 - Dieter Reith [Krabs in the hospital]
• Steel Licks 8 - Jeremy Wakefield ["...help you do it myself."]
• Steel Licks 9 - Jeremy Wakefield ["Wow, he really does care."]
‣ Comic Walk - Sidney Torch [at the dump]
‣ Towerstreet 17 [#23] - Gerhard Narholz [Krabs moved to the hallway]
‣ Furtive Footsteps - Paddy Kingsland ["Well, that's Mr. Krabs' mattress all right."]
‣ Dream of Tomorrow - Trevor Duncan ["Isn't it beautiful, Patrick?"]
‣ Lumbering Giant - Paddy Kingsland [Squidward accidentally woke up the guard worm]
‣ Dramatic Encounter - Gregor F. Narholz [the worm attacks Squidward]
‣ Classic Soap 14 - Dieter Reith [meanwhile at the hospital...]
• SpongeBurgler - Nicolas Carr [SpongeBob and Patrick in ski masks]
‣ Dangerous A - Mladen Franko [SpongeBob and Patrick making noise]
‣ The Creature (a) - Gregor F. Narholz [worm roars at them]
• Hello Blues - Sage Guyton, Jeremy Wakefield [wooden spoon]
‣ Finders Creepers - Paddy Kingsland [Squidward about to take the mattress]
• Steel Licks 6 - Jeremy Wakefield [worm attacks Squidward again]
‣ Classic Soap 14 - Dieter Reith [back at the hospital]
• Gator - Steve Belfer [SpongeBob and Patrick dressed as choice cuts]
‣ Towerstreet 17 [#4] - Gerhard Narholz [Krabs rolling toward the dump]
‣ Towerstreet 17 [#41] - Gerhard Narholz ["Run, Mr. Krabs!"]
• Harp! - Nicolas Carr ["It's... me money!"]
‣ Romantic Ending [#34] - Harry Bluestone, Emil Cadkin ["I promise I'll never leave you alone again."]
• SpongeBob Closing Theme - Steve Belfer, Nicolas Carr [Krabs barks at SpongeBob and Patrick]
• Sponge Monger - Sage Guyton, Jeremy Wakefield [ending]
- This episode is available on the Where's Gary? DVD and VHS, Season 4 Volume 1, Triple Pack 4, Big Hits: Volume 2, Favorite Episodes Volume 2, 2-Movies-Edition, Double Feature Volume 2, SpongeBob SquarePants Vol. 5, From the Beginning, Pt.2, 2-Season TV Pack, The Ultimate SpongeBob Box Set, The SpongeBob SquarePants Collection, The SpongeBob SquarePants 8 Season DVD Collection, Complete Fourth Season, First 100 Episodes, The Third & Fourth Seasons, and The Best 200 Episodes Ever DVDs.
- "The Lost Mattress" was ranked #67 during the Best Day Ever event from November 9–10, 2006.
- The closed/open sign is usually located on the doors of the Krusty Krab, but in this episode, it is on the windows.
- In this episode, the Krusty Krab key looks normal. However, in "Patty Hype," the key has two "K"s located on the side.
- It is revealed that Mr. Krabs keeps his money under his mattress.
- This was Tim Hill's first time working on an episode since "Jellyfishing" in 1999.
- Mr. Krabs normally sleeps on a hammock, but in this episode, he sleeps on a mattress, which is one of the only times it has been seen.
- Mr. Krabs says he does not know what a bank is, although, in "Krabby Land," he said he was going to the bank.
- Squidward breaks the fourth wall by looking at the camera when he says, "Oh, that figures."
- In the Polish dub, the episode's title is called "Afera materacowa," which translates to "The Mattress Wrangle."
- In the Croatian dub, Patrick says that there's only "hundred" mattresses instead of ten.
- This episode marks the first usage of "Happy Sponge Chase Vibes" and "SpongeBurgler."
- This episode also marks the first appearance of Guard worm.
- This is the second episode where Squidward is repeatedly attacked by an animal. The first was "The Camping Episode."
- Squidward almost sends a death threat to SpongeBob by saying "I am going to mur-..." before being cut off by the police. It is strongly implied that he would have said "murder," which would have gotten him in even more trouble.
- Thus, this is the first time Squidward almost kills SpongeBob.
- Irony: SpongeBob, Patrick, and Squidward could have removed Mr. Krabs' money from his old mattress before throwing it away, and put it in the new one.
- This is Patrick's first appearance in season 4.
- The scene where the mattress store employee closes the controller box on SpongeBob's hand is a reference to a similar gag from the film Pretty Woman.
- The road that leads to the front door of the Krusty Krab is replaced with sand when the characters are there.
- When SpongeBob is sobbing in front of the Krusty Krab, the camera pans out, and the Chum Bucket does not appear.
- When SpongeBob's face moves to the other side of his body, his pants are on the side where his face was before. In the next scene, his pants are on the same side that his face is on.
- When Mr. Krabs opens the Krusty Krab, there is a keyhole on the door handle. In the next scene, it is gone.
- As SpongeBob and Patrick enter the mattress store and they exclaim "Wow!" SpongeBob's buck teeth are missing.
- Right before the Mattresses and then some employee walks up to SpongeBob and Patrick, SpongeBob's eyelashes are missing for a second.
- When SpongeBob and Patrick are making the card for Mr. Krabs, the Galley Grub sign is in front of the boat. Usually, it is aside from it.
- When Squidward appears being bit on the butt by the worm, his neck is missing. This error was fixed in the Where's Gary? DVD.
- Outside the hospital, before Administration Flotsam is heard talking to Dr. Actor, Mr. Krabs is not outside the hospital on his stretcher near the front entrance until the nurse gets outside and pushes him down.
- Patrick changes into the meat costume in the outhouses/closets that were not originally there in the scene of the dump.