The day starts off quite well for Squidward. He is about to practice his clarinet when SpongeBob's alarm clock (facing out the window) knocks the clarinet inside Squidward's mouth, and SpongeBob asks Squidward if he wants to go jellyfishing. Squidward tries to reply, but because his clarinet is in his mouth, making anything he says incomprehensible. SpongeBob thinks he said yes. After Squidward takes his clarinet out of his mouth, Squidward is constantly bothered in his house by SpongeBob and Patrick who want to go jellyfishing with him. Squidward, in an attempt to stop SpongeBob and Patrick bothering him, tells SpongeBob that he should be at work, but SpongeBob tells him that it's a Sunday, and that the Krusty Krab is closed on Sundays.
Squidward tells SpongeBob and Patrick to stay where they are, and goes out the back door of his house and goes into the Krusty Krab . He sees SpongeBob and Patrick looking for him, and goes into the kitchen. SpongeBob and Patrick are still looking for him, so he goes into the freezer. After SpongeBob and Patrick go away, Squidward is frightened to find that the handle is jammed, and that he is stuck inside the freezer. He assures himself that someone will find him, but he becomes frozen and is stuck there for 2,000 years.
SpongeTron, a descendant of SpongeBob finally discovers Squidward after a hinge snaps off and the door breaks down. After being defrosted by SpongeTron, Squidward finds out that everything in the future (except for people) is made entirely of chrome, and all organic life forms that aren't people (such as seaweed or kelp) are simply spray-painted chrome. SpongeTron introduces Squidward to his clones, SpongeTrons X, Y, and Z. He also informs Squidward that there are 486 SpongeTrons in response to his question "Are the other letters of the alphabet involved here?" meaning that the English alphabet has been expanded, merged with another character set, or (most likely) it was hyperbole by the writers to make the future more complex. Squidward decides that he hates the future, so SpongeTron directs him to a time machine, which is actually a small room with a control panel. Shortly after meeting Patron, a two-headed descendant of Patrick, Squidward goes into the can opener, and then goes into the time machine to travel to the past, ripping the entire room out of the building in the process.
Squidward winds up in early prehistoric times, where he meets the primitive ancestors of SpongeBob and Patrick, who are torturing themselves with a jellyfish. Squidward introduces jellyfishing to them, and they seem to be interested until Squidward starts playing his clarinet, which drives them crazy, causing them to chase after him.
He goes into the time machine, but he accidentally malfunctions it by pulling the lever so hard that it breaks, causing the time machine to go all around the dimensions. The time machine got flatter and flatter and it disappeared, and Squidward ends up in a surreal realm of nothingness, with a strange atmosphere (A strange bass tone, very weird echoing voices in the background, and large rectangles which disappear when Squidward touches one of them). At first glance of the realm, Squidward is relieved to finally be away from SpongeBob alone with his clarinet (and is later echoed by the surreal echoing voices). Suddenly being freaked out by voices, he attempts to escape the realm by running (which takes him where he already was) and stomping the ground in frustration. He breaks through the floor, landing in the time machine room. He begs it to return to the present, stating how much he misses Bikini Bottom, his Easter Island head, and even SpongeBob. The machine reactivates, sending him back to the present and reuniting him with SpongeBob and Patrick. He tells the two about how happy he is to see them both, but once again he is driven to anger when they ask him about Jellyfishing once more. He asks who invented that game in the first place, only for SpongeBob and Patrick to tell him that he invented it, making Squidward realized he invented Jellyfishing in his travels. He simply proclaims; "I'm going back", concluding the episode.
( ‣ ) Associated production music
( • ) Original music
( ◦ ) SpongeBob music
‣ ? [title card] ‣Hawaiian Blues - The Hawaiian Serenaders [opening] •SpongeBob Closing Theme - Steve Belfer, Nicolas Carr [SpongeBob and Patrick at Squidward's door] ‣The Rake Hornpipe - Robert Alexander White [Squidward hides in the Krusty Krab freezer] ‣Death Trap - Gregor F. Narholz [the door's locked] ‣Hawaiian Link (b) - Richard Myhill ["I'll be out of here in no time."] ‣House of Horror - W. Merrick Farran [2000 years later] •SpongeBob Closing Theme - Steve Belfer, Nicolas Carr [Squidward in the future] ‣The Gypsy Violinist - Dick Stephen Walter ["I don't belong here."] ‣Aloha Oe - Hans Haider, Queen Lili'uokalani ["I got to get home to my own time period."] ‣Dorothy - Tony Tape [inside the time machine] ‣ ? [time machine disappears] ‣ ? [Squidward in the past] ‣Lovely Scenery C - Mladen Franko [prehistoric SpongeBob revealed] •SpongeBob Closing Theme - Steve Belfer, Nicolas Carr [Squidward invents jellyfishing] • ? - Brad Carow [Squidward playing clarinet] ‣Dangerous A - Mladen Franko [prehistoric SpongeBob and Patrick chase Squidward] ‣Dorothy - Tony Tape [inside time machine] ‣ ? [time machine disappears] ‣ ? [Squidward in a blank white void] ‣Dorothy - Tony Tape [inside time machine] ‣ ? [time machine disappears] ‣Hilo March - The Hawaiian Serenaders [ending]
As of October 30, 2013, The Internet Movie Database (IMDB) gives this episode a rating of 8/10 based on 116 ratings by users. TV.com users give this episode a 9/10 based on 197 votes.
This is the one of the few episodes where the opening credits do not appear in an underwater background. The other is "Krusty Krab Training Video."
This is the only episode where the episode's name is spoken when the title card appears.
According to Tom Kenny, this episode is the most surreal episode in the SpongeBob series.
Along with "Karate Choppers," this episode aired on December 31, 1999, the final day of the twentieth century.
The Serbian name for this episode is SB-192.
This is the only time the title card letters are floating.
The episode, which arises from Squidward time-traveling and inventing the game of jellyfishing while seeking to avoid SpongeBob and Patrick as they want him to jellyfish with them, is a time paradox known as a causality loop. Thus, a person is inspired or driven by an event to time travel and, whether or not intentionally, causes the event which will facilitate their initial time travelling trip.
The background of this episode's title card is also seen in "Can You Spare a Dime?" when Squidward pictures himself as an astronaut.
The future is chrome after 2000 years. However, in "SpongeHenge," Jellyfish Fields is still as it was after 3000 years. Either Jellyfish Fields was never made chrome, or after 1000 years, everything was reinstated as they were before the chrome transformation.
The episode "Ugh" appears to take place after the prehistoric time period shown in this episode, as the primitive characters in that episode are more civilized and have developed a simple language. Three scenes of this episode can even be seen during the song "When Worlds Collide."
The episode's title, "SB-129", is a portmanteau of the show's abbreviation, the first season, and it being the twenty-ninth episode in the series: SpongeBob - Season 1 Episode 29.
In the PC version of The SpongeBob SquarePants Movie video game, SpongeBob can look into his future with the Pool of Perception. The third time he looks in, he sees the forty-fourth century, which resembles the future seen in this episode.
This is the first episode to involve time travel. The second was "Back to the Past."
The future version of Patrick is Patron. In Spanish dubbing, the name is the same. Ironically, "patron" is another Spanish word for "jefe" which translates to "boss".
In Nickelodeon of Southeast Asia during the marathon of Squidward's big holiday contest, this episode was known as SpongeBob 3000.
This is the first episode to have everything covered in chrome. The second was in "Procrastination."
When Squidward is in "nowhere", his footsteps make different sounds than usual.
SpongeTron mentions that he has 486 clones, one for each letter of the alphabet. This means over the course of the two thousand years, four hundred sixty more letters have been added to the alphabet.
In the future, the entire Bikini Bottom is chrome, except for the hinges on the freezer door, which had been rusted over the last 2,000 years, the freezer's interior, the time machine's interior, and the Bikini Bottom civilians.
The jellyfish are smaller in the past, compared to the present day's jellyfish.
This is one of the few episodes in which the Krusty Krab is featured without Mr. Krabs.
In Poland version, SpongeTron is called SpongoBot and Patron is called Patrickobot.
This episode is considered by some to be non-canon for several reasons:
Although if you consider the end of the episode, Squidward returns to the same day. Which means that although he froze himself earlier that day, he would have returned to work.
Over the two thousand years (March 6, 2017 - March 6, 4017) no one entered the freezer to get supplies needed to supply the Krusty Krab with its products, as the freezer contains frozen Krabby Patties. Otherwise, they would have seen Squidward in there. The most recent time when someone entered the freezer was Evil Spatula, which aired on March 9, 2013.
A theory of this episode is that there are two Squidwards for the rest of the SpongeBob series onward. One of which is still trapped in the freezer and will be for two thousand years, and the one who already was frozen for two thousand years, went back to the past, and then returned to the present.
Nobody knows SpongeTron could know Squidward's name. Squidward never told him.
This is one of the few episodes in which many characters make their debut.
This episode premiered on New Year's Eve of 1999 along with several other Nicktoon episodes with futuristic themes in celebration of the new millennium.
Primitive sponge and Star are similar to Spongegar and Patar from the episode Ugh.