SpongeBob goes to boating school and during the test he continues to crash into the same two cars, inflating Mrs. Puff every time he continues to crash into an obstacle. Mrs. Puff then inflates so much, she sends the car airborne. SpongeBob then crashes the car into the lighthouse of the boating school, critically injuring Mrs. Puff.
In the hospital, the purple doctorfish clarifies that Mrs. Puff's inflation sac (the part that pufferfishes use to puff up) was popped in the collision and she will not be able to "puff" again. Mrs. Puff is extremely angry and begins grabbing his nose and threatening him. She is tranquilized to stop her from hurting him. SpongeBob then begins to ramble and the doctor tranquilizes him as well, saying that everyone needs to take a nap.
SpongeBob then visits Mrs. Puff with a bouquet of flowers along with the hundreds of other flowers he sent her, which she appears to be allergic to. After forcing her into a wheelchair, he pushes her down the hallway. Doctors are seen sprinting through the hallway with muscular men on the gurneys. SpongeBob stops the purple doctorfish and asks what was going on. He replies the Demolition Derby members are about to battle in the hospital room, where they appear to be hitting each other with wheelchairs. The purple doctorfish says that they are brave to risk their lives for the community's entertainment. Mrs. Puff imagines them smashing into SpongeBob and killing him and begins laughing hysterically. Her laughing attracts SpongeBob's attention, and she claims she has a way for him to earn "extra credit."
She talks to Captain Lutefisk asking him if she can enter SpongeBob. She shows him how much damage SpongeBob can do with a boat, though he is just using a steering wheel. Lutefisk says he is perfect for the derby and puts a sock on his head, giving him the title "Le Squish." At the derby, SpongeBob is unaware of what he is supposed to do, which is to take out the opponents. Seeing him as an easy target, some competitors ram into him but are unable to hit the car and are all hit by SpongeBob or destroyed in another way by the car. SpongeBob carelessly drives around everywhere, eliminating everyone.
Mrs. Puff is enraged at how SpongeBob is defeating the competitors only by serendipity. She then chases the driver away from a tractor and steals it. She then starts to chase SpongeBob, trying to crush and kill him. She is unsuccessful as SpongeBob avoids her and all the cars are crushed before she breaks the wall and starts chasing him off-road. They then collide into the boating school after Mrs. Puff chases SpongeBob for a while. She regains her "puff," which SpongeBob notices and they get injured by the school, which breaks into large pieces that crush them.
According to the storyboard, after SpongeBob went down the rail, the other skaters were originally going to say "Dude!" This was cut for unknown reasons.
This is, by far, Mrs. Puff's darkest role in the series, as she had lost her sanity because of her life-changing accident combined with years of putting up with SpongeBob. In "Bumper to Bumper," Mrs. Puff gets really angry at SpongeBob for failing the test many times.
This is also the darkest role any character or group of characters had in the franchise, as Mrs. Puff actually wants to brutally and violently murder SpongeBob. It is also the only time a character (besides the Tattletale Strangler and Dennis) hunted down someone to kill them or created a plan to kill a specified person, whereas every other time the person or people would normally move around attacking random people or in the case of committing a crime or one of Plankton's attacks sometimes, threatening to attack someone with a dangerous weapon (or one that has serious effects without doing any actual damage in the case of Plankton), both of which are usually either not fatal or not directed at a specific reason.
For these many reasons, this episode is hated by most fans and is rated PG in Canada.
The Purple Doctorfish said "Come look at this week's casualties." Casualties are people who have been injured or killed in a serious accident.
This is the second time Mrs. Puff has been flat. The first time was "Patty Hype" when she makes a cameo in the Pretty Patties crowd.
This is the second time Mrs. Puff is completely deflated. The first was "Pranks a Lot."
The plot is similar to "No Free Rides," because Mrs. Puff gets sick of SpongeBob failing, and she wanted him out of her class (although it is taken to extreme proportions including killing him here). Then, she plans something for SpongeBob and covers it up as Extra Credit.
Captain Lutefisk is a reference to the WWE wrestler Captain Lou.
Captain Lutefisk's name is also a reference to a dish made from fish called, "Lutefisk."
At the part where SpongeBob is pushing Mrs. Puff down the hall in Mrs. Puff's wheelchair, one of the pictures looks similar to the logo used by Apple Inc.
This episode "Demolition Doofus" is named after a type of entertainment involving crashing cars into each other called a "demolition derby."
When The Kruncher was driving away from SpongeBob, after SpongeBob drove over him, The Kruncher's back fins was missing in that shot. There was another shot that also showed his missing back fin.
Oddly, even though Captain Lutefisk introduced the four drivers and SpongeBob, there was another unknown driver that tried to crash SpongeBob along with Blow Torch and Divin' Bell Dale. Those three also drove into another unknown fish that may be also competing in the derby.
In the part where SpongeBob says "Oh dear, I think I'm in that Fellow's way," his voice is higher pitched than usual, This error also occurs in "Little Yellow Book."
There is a part of the episode where SpongeBob drives on Blow Torch's face, according to the gravity (which is like real-life), SpongeBob should have squashed him instead of being balanced on his face. It may be that the sea has different gravity, which might explain how SpongeBob floated on to his face.
It's unknown what gave Mrs. Puff her "puff" back at the end of episode. It's also unknown if she lost her "puff" again.
Despite being arrested in other episodes, she doesn't get arrested here, despite her trying to murder SpongeBob. Since the crime was committed at the end of the episode and police were not chasing her, it can be assumed that they were unaware of anything until after the episode's events.
Mrs. Puff's hair outline turned black on two occasions, as she, and SpongeBob watched the derby inside the hospital.
When SpongeBob jumped out of the water (as a real life kitchen sponge), his sock mask was missing.
Nat Peterson's lips were a pale yellow in one scene, then blue in the next scene.