Francis comes home from Marlin Academy to visit for the weekend, while Lois and Hal are away. Malcolm overhears them wonder if he's a mature adult and different than the delinquent he is before.
Lois and Hal are spending the weekend at a family wedding, leaving Francis -- home for a visit -- in charge. When Malcolm overhears them discussing whether Francis has spent long enough at the military academy, he enlists his brothers in a scheme to get Francis home by preventing any of the usual disasters. But three of Francis's dude buddies turn up to party and trash the house, and while frantically cleaning up Malcolm gets a serious head injury that necessitates the usual trip to the emergency ward. Meanwhile, Hal and Lois discover that his family has a new nickname for her: "Lois Common Denominator." Her humiliation provokes Hal to declare his devotion to her.
- This episode's title is a homage to the Home Alone franchise. By the time this episode was made, the franchise had made three movies and so this was titled "Home Alone 4" as a joke sequel on that.
- In 2002, they actually would have come out with a Home Alone 4.
- The initial cold opening for this episode is the family sitting around a table and Reese making a joke, saying he's going to fling mashed potatoes at Lois, only for her to take it seriously and start an argument. However, this was only seen on the first airing of the episode. In all syndication reruns, the cold opening from Krelboyne Picnic (where Hal and Lois are forced to get out of bed because the boys are causing a bunch of chaos), takes it's place. In the DVD version of the episode, the original cold opening is in it's place.
- This episode reveals that Caroline Miller is either sexually or romantically intimate with the school janitor.
- First episode where Francis is in the house with the family.
- This episode reveals why Francis got sent to military school. It was because Lois had specifically told him not to get his nose pierced, with the threat that he'd get sent to military school. Just so that he could spite her and prove his freedom to her, he did exactly what she told him not to do and got himself sent straight to Marlin Academy.
- In Pilot before this episode, everyone thought Francis was sent to Marlin Academy because he got arrested for destroying a car and having sex with his girlfriend.
- Almoa Wright plays the role of a sassy black nurse in this episode. Aloma Wright would shortly after be cast to play the role of Nurse Lavene Roberts. A character in Scrubs who has the exact same role and personality as this one.
- Lois says that sending Francis to military school was the best decision she ever made. However, she would later admit that is was a big mistake in the episode Ida Loses a Leg.
- The episode reveals why the family is poor due to the boys' constant accidents that lead to incurring hospital bills.
- This episode introduces Hal's family's disappointment in him marrying Lois that lead to her being called Lois Common Denominator. Family Reunion later reveals their shared disgust with Victor and Ida in Hal marrying her against their wishes and wanted him to marry Susan.
- While Malcolm, Reese, Dewey, and Francis are deliberately making their house messy, you can see right above their ceiling a bright light shining down and a black background. It shows that they film their interior of their house on a set.
- After Malcolm gets his head injury, his forehead can be seen under the raw meats with no damage. Not even makeup was added to give the illusion of a serious injury.
- When Reese, Dewey, and Francis are taking the bandaged up Malcolm to the car, you can see the reflection of the camera crew in the windows.
- [Malcolm has caught Reese and Dewey fighting]
- Malcolm: Guys, quit it. Listen for a second. I just heard mom and dad talking. They're thinking of letting Francis come home.
- [Reese takes Dewey off his shoulders and they listen to Malcolm]
- Reese: You serious.
- Malcolm: Yeah. They want to see how he does with us this weekend. So we can't screw up.
- Reese: Cool, let's go tell him.
- Malcolm:[stops Reese] No. You know how Francis gets when people tell him what to do.
- [Flashback with Lois confronting Francis as she's making dinner.]
- Lois: I am warning you. If you get your nose pierced, you are going to military school and I mean it really. Do you hear me?!
- [Francis smiles in defiance and later comes home with a bunch of nose piercings]
- Francis: Hey mom. What's for dinner?
- Lois: Lois Common Denominator.