"Jeffy's Mistake!" is the 229th episode of SML Movies.
Jeffy wears a Pooperman shirt and he poops. Jeffy then sticks his hand in his butt and sniffs it. Rosalina visits and she mentions that Mario promised her that they would have a date together. But Mario is worried about Jeffy being home alone. Jeffy then puts his poopy hand at Mario causing him to freak out.
Rosalina then says it can't be that bad until she smells it. Mario goes to the bathroom and sees if Shrek can take care of Jeffy until he says that he will stay in there all day creating biochemical warfare. Rosalina then makes a joke that Jeffy is pooped out and asks Mario if Black Yoshi can babysit Jeffy. However, Mario says he might not do it. Meanwhile, Black Yoshi is making Kool-Aid Cupcakes and Mario asks if Black Yoshi can babysit Jeffy and let him play his Xbox One.
Black Yoshi gets his gun and points it at Mario but Mario says Jeffy can play games but Call of Duty (since because COD is not child-safe). Black Yoshi says he needs $400/$500, but Mario says he can buy him an Xbox One with that. Black Yoshi, says he would do it for $200. Black Yoshi then eats a watermelon lollipop. Black Yoshi decides to babysit him and introduces Black Yoshi to Jeffy.
Then, Rosalina and Mario go and Jeffy wakes up until he says he can't see anything, but Black Yoshi says the helmet is over his eyes. Black Yoshi lets Jeffy play Grand Theft Auto (which Black Yoshi is stupidly irresponsible with a kid). Jeffy plays GTA but he dies in the game and yells. He then grabs Black Yoshi's Xbox One and throws it off the balcony. Black Yoshi comes and Jeffy says sorry, but he ties up Jeffy. Mario comes home and wonders what is going on. After reasoning with Black Yoshi, he goes to Gamestop and tries to trade it for money, but it won't work. Then, Black Yoshi shoots Jeffy, but it is just a dream. Jeffy says that he pooped Mario's bed and Mario is triggered.
- This is the first time Jeffy has a different pose in thumbnails, and the first time his 2nd main pose is shown.
- This marks the first (and only) appearance of Boss Carson.
- The SML question for this video is used again in Jeffy's Tantrum!
- This marks the 5th mistake video.
- 6th is Black Yoshi's Mistake!
- What Jeffy does at the beginning of this episode is basically what he said Mario did to him in Jeffy's Bad Word!, as he puts his hand in his butt and then sniffs it.
- This is 2nd spinoff mistake video since an original series from Toad's Mistake and 1st spinoff video from Chef Pee Pee's Mistake.
- This is the first time Black Yoshi meets Jeffy, but this is only a dream so the two characters never met.
- This is Shrek's first appearance since Mario's Hobo Problem!
- This episode reveals that Mario and Rosalina are still together after Jeffy's Bad Word!
- Jeffy is the third character to have a video based on their mistake, the first and second being Toad (3 times) & Chef Pee Pee.
- This is the 4th Dream video to be uploaded.
- This is the third time we see a character destroy a video game console. The first being Black Yoshi's Call of Duty Black Ops 3! and the second being Bowser Junior's Nintendo 3DS.
- Jeffy being blown up could be an apology for Jeffy's Bad Word!
- This is the second Mistake video that featured Black Yoshi, the first being Toad's Mistake 2.
- This is the 4th time Rosalina uses foul language, 1st in Jeffy's Homework!, 2nd in Jeffy's Cellphone!, and 3rd in Jeffy's Bad Word!.
- 5th is Jeffy And The Beanstalk!
- When Jeffy grabs the Xbox a box of Play-Doh and the Nintendo 64 logo can be seen in the background.
- This is the second times Jeffy dies, the first being Bowser Junior's Nerf War!. Although it was just a dream.
- This is one of the few episodes where Jeffy doesn't smack his Diaper, The first being Jeffy Gets Potty Trained!, The second being Jeffy's Cellphone!, the third being Bowser Junior's Game Night 4.
- This episode was demonetized according to an Instagram post.
- When Jeffy threw the Xbox out the window, Logan used Elaina's apartment rather than his because he needed to find a space to throw the Xbox where there were no cars parked.
- Mario and Black Yoshi being triggered is a reference to SOCIAL JUSTICE WARRIORS.
- Jeffy throwing the Xbox off the balcony is similar to the Psycho series made by McJuggerNuggets, where Psycho Dad always destroys game consoles that belong to Jesse. Coincidentally, Black Yoshi wanting to kill Jeffy for payback of destroying the console is also similar the Psycho Series where Jesse plans to kill Psycho Dad for ruining his games.
- When Jeffy throws Black Yoshi's Xbox One off the balcony, he has his normal shirt. But when he says "I'm sorry," and Black Yoshi gets triggered, he has his Pooperman suit on instead.
- It is unknown how Jeffy quickly got the Xbox as soon as Black Yoshi came.
- However, due to the whole episode being a dream, these mistakes can be explained. This is because weird things sometimes happen in dreams and not in reality.