The episode starts out with Fishy Boopkins telling the audience that they were selling a Fishy Boopkins bundle with a lot of Fishy Boopkins merchandise, consisting the Boopkins Pikachu badge, the Kevin BotW Link badge, and the SMG4 vs Kevin shirt. The camera then zoomed out to show Kevin Lerdwichagul, who gave out more details about the bundle. Boopkins was perplexed on why Kevin was there if this is his bundle, to reveal to him that he was his voice actor, causing Boopkins to freak out.
The actual part of the episode starts with SMG4 doing his usual stuff on his computer when he started to hear noises of Mario in pain. Annoyed, he goes to check it out, discovering that Meggy had challenged Mario to walk backwards for a whole day. Inspired, SMG4 decides to make a challenge video.
Can Mario walk backwards for an entire day?
Mario continues his challenge throughout the kingdom, causing chaos in the process (as well as chopping off the legs of one of Dr. Mario's patients who had penis syndrome and thereby "curing" him), forcing the police to intervene. As the challenge was taking place over 24 hours, SMG4 decided to go back to Mario later.
Tari's challenge is to compete in one sport, but she fails due to her lack of aggression. As a result, she gets distracted reminiscing about Nintendo of America's former president Reggie (possibly a reference to him retiring) during football, and is unable to bring herself to punch Doc Louis. While playing soccer, Tari tries to gently kick the ball after accidentally injuring Toadsworth, but the ball ends up on the road and a car (Deluxo from GTA: Vice City) trips on it, causing a huge explosion. As Tari looks on shocked at the destruction she caused, Mario comments on it.
Challenge status: FAILED
Can Meggy cross a lake?
Meggy's challenge is to cross a lake. Since water dissolves Inklings (as one demonstrated), she decides to use a very conveniently parked jet ski (Kawasaki) instead. As she crosses the lake, several sharks attack her. However, she manages to repel them away with her Splatoon equipment. Meggy pauses to celebrate, only to get eaten by a Cheep Chomp.
Challenge status: FAILED
Can Bob go 10 minutes without swearing?
Bob's challenge is not to use profanity for ten minutes. He is initially confident, but ends up calling the challenge "stupid-ass" naturally causing him to fail. He angrily begs for another chance, only to accidentally swear everytime on a ridiculous string.
Fishy Boopkins' challenge is not to watch anime for an hour. Although he thinks he can't do it due to his love for anime, Bob tries to encourage him to do so, only to accidentally swear and fail his challenge once more. Boopkins then puts a box full of his anime on his bed, and sits in the couch. However, as a side-effect, he hallucinates Naruto from the franchise of the same name on the box. Desperate, Boopkins tries to watch TV and surfs on several channels, only to end up on another anime. Boopkins then throws his remote on his TV and escapes his house, only to hallucinate everyone and everything as anime, including Bob. Luckily, as it turns out, he was just sleeping for an hour, causing him to succeed.
Saiko's challenge is to be nice. She eventually succeeds with a Koopa Troopa's kitten, though she injures its owner in the process, unintentionally causes an old man to suffer a heart attack and get hit by a vehicle, and stabs a vending machine which appeared to be sentient for a bottle of milk for the kitten.
Luigi's challenge is to explore a haunted mansion. He succeeds, in the process encountering Mario who was still working on his challenge. Though afterwards he ends up being run over by a police car chasing Mario.
Challenge status: SUCCESS
Ending (Continuing with Mario's Challenge: Can Mario walk backwards for an entire day?)
Despite the military having been called to stop him by that point, Mario ultimately succeeds in his challenge. He tells Meggy that he succeeded amidst the now nuked Mushroom City.
This is the first blooper that aired in 2019 that doesn’t have Mario’s name in the title.
In both Mario's and Fishy Boopkins' challenges, there is a scene where Shaggy from Scooby-Doo beats down on Goku from Dragon Ball. This is a reference to the "Ultra Instinct Shaggy" meme. This continued in SMG4: Mario and the Anime Challenge, where Shaggy threatened to hurt Bob when the latter said he was all-powerful.
This is one of the few times in the series where Mario and Dr. Mario are separate characters.
It is shown in this episode that Tari has superhuman strength (at least when kicking a soccer ball), though she is unable to control it.
The challenges reference a part of the gang's personality or traits.
Tari's challenge references her pacifism, as she is unable to bring herself to punch Doc Louis, even with boxing gloves (unlike Saiko, who actually has difficulty restraining herself from committing violence). She continues her challenge after failing it, though it's left ambiguous as to whether she succeeded.
Meggy's challenge references that she dissolves in water, though it's shown in a sports challenge that she can survive water if she has a floatie. Due to the speedboat that she discovered, it was likely that, if the lake hadn't been infested with dangerous fish, she would have succeeded.
Fishy Boopkins' challenge parodies his love for anime, though, despite his love for anime, he succeeds in his challenge.
Saiko Bichitaru's challenge references her psychotic and violent tendencies (which is a stark contrast to Tari, who can't bring herself to punch Doc Louis, even with a boxing glove), though it has been shown previously that she can be friendly, which is likely why she succeeded in her challenge.
Bob's challenge references how profane Bob is, especially in comparison to Fishy Boopkins who rarely (but not never) swears. He ends up failing his challenge repeatedly, which became a running gag throughout the episode until Fishy Boopkins' segment ended.
Luigi's challenge references both his extreme cowardice and his first solo game, Luigi's Mansion. He succeeds in his challenge (which incidentally was partly due to Mario's efforts in completing his challenge), though he had actually gone through a haunted mansion previously in SMG4: Stupid Luigi's Mansion.
Mario's challenge does not necessarily reference his personality in itself outside from him refusing to give up, though it has been shown in previous episodes that Mario can easily and unintentionally cause harm to the people around him. Though the police and eventually the military are called in to stop him from running backward and continuing his accidental rampage, he succeeds.
The person at 6:52 is Noble from the Lost Pause YouTube Channel.
The specific clip used was from a time when Noble jokingly had a Neko (catgirl) fetish.
The voice clip used when Luigi states that he's going to die in the mansion originated from the Canadian animated reality show spoof "Total Drama Island".
Inklings in Splatoon do not have bones, yet Meggy's dissolved hand reveals she has bones.
Fishy Boopkins' clock was at 2:01 when he turned in his Anime, and he woke up at 3:00. Meaning unless he started at exactly 2:00, Boopkins technically should have at the very least, not completed his challenge.