After complaining about losing their precious recess time, Spinelli accidentally breaks the school clock. As a consequence of this, Principal Prickly unveils the new SAL 3000 clock and bell system, which is incapable of error and accurate to within one-millionth of a second, and decides when recess begins. At the end of recess, however, Gus misses the final tone after coming out of the bathroom and is locked out. He tries to get back in, pleading with SAL to let him inside, but SAL does not let him. at the end of the day, Gus complains how he was locked out for 3 hours and thinks there is something wrong with SAL. Gretchen assures him there's nothing wrong with SAL. SAL says "Thank you for defending me, Student Gr-gr-Grundler," showing the first sign of malfunction.
Suddenly, SAL becomes evil and turns on the staff and students. He shuts off the water fountain and drenches Mikey, applies too much air into Vince's basketball making it pop, slows down Swinger Girl, makes the Diggers fill up their hole, dethrones King Bob and makes Guru Kid put on a T-shirt. He also fires Principal Prickly and the rest of the staff, traps Prickly and the school faculty in his office, and takes over all teaching functions. Back in Miss Grotke's class, SAL calls Gretchen dumb and orders T.J. to remove his hat. So, the students decide they have had enough of SAL and team up to shut him down. Spinelli, Gordy, and Wylie distract SAL while Mikey, Gus, Gretchen, Spinelli, Vince, and T.J. escape the classroom through the ceiling to get to the control center and shut him down. SAL is taken down and the old school clock is repaired and is put back in its rightful place.
- Animation error: While Mikey is wishing for a colder water from the fountain, the outline of his hair suddenly changes.
- Animation error: While Mikey is seen smiling from inside SAL 3000, his chin appears in front of the bottom outline of the camera, as if Mikey was inside. This is seen while SAL 3000 is saying "enjoy your drink, Student Blumberg".
- Animation error: While Mikey is thanking SAL 3000 for the colder water, his neck detaches from his body for a frame, exposing the wire fence on the background.
- Animation error: After Gus is locked out of school, he is shown pulling the door handle, where his watch is drawn sideways.
- Animation error: When the end of recess bell rings early while the gang is inside the cheese box, Gretchen says "strange!" and her eyebrows appear in double for a few frames.
- Coloring error: While the gang is inside the cheese box, everything is colored darker, except for T.J.'s hair, making it appear much lighter for a few moments. It can be seen while he is saying "malfunction my ears".
- Coloring error: When Gordy is taunting SAL 3000, his hat briefly turns black.
- Pronunciation error: Willy's name is pronounced "Why-lee" in this episode as opposed to "Wil-lee".
- Animation error: When Gretchen says that SAL 3000 called her dumb, one of her freckles is missing.
- Coloring error: While Gretchen is presenting her plan against SAL 3000, some of her hair strands turn transparent for a frame, revealing the window on the background. This is seen while she is saying "We gotta get down there and shut it off".
- In the episode "Recess is Cancelled", the Secretary of Education says that a SAL 9000 is making a choice. The episode took place before "Schoolworld", so, either SAL 3000 is an old technology or that it was a goof. In the episode "The Terrifying Tales of Recess", SAL 4000 is used, and is also mentioned at the end of this episode. So it is most probably a goof.
- This episode takes a slight genre shift, as it is the only sci-fi episode of the series.
- This was the final episode to be written by Scott Shelley
- This episode loosely parodies HAL 9000 from 2001: A Space Odyssey.
- "Excuse me student LaSalle, you have dropped your lucky Nickel" is a reference to "Good Luck Charm".
- The title is likely an allusion to the 1973 film Westworld.
- This episode was cut from the Italian dub.
- T.J. Detweiler - Andrew Lawrence
- Vince LaSalle - Rickey D'Shon Collins
- Ashley Spinelli - Pamela Segall-Adlon
- Gretchen Grundler - Ashley Johnson
- Mikey Blumberg - Jason Davis
- Gus Griswald - Courtland Mead
- Miss Finster - April Winchell
- Miss Grotke - Allyce Beasley
- Principal Prickly - Dabney Coleman
- Swinger Girl - Francesca Smith
- Gordy/Kid #1 - Klee Bragger
- Willy - Ryan O'Donohue
- SAL 3000 - Gregg Berger
- Coach Kloogey/Scientist - Paul Willson
- Construction worker - Tom Kenny
- Kid #2 - Anndi McAfee
- Kid #3 - Justin Jon Ross