All the events in the show— the randomly reappearing background extras, important plots being dropped for no reason, the frequent ass pulls— makes more sense when you realize the show is all in Allen's mind. Given the show's eight-season run, it's clear Allen lost interest and just started making up random stories.
In the first season, we saw most of the extended Spencer family in jail. In the subsequent seasons, they're never shown. It's possible that they were released from jail, given that we do see some other Spencer family members that were never in jail (Cousin Lomax and Uncle Lester).
Anastasia is rarely shown outside of the house as much as her son and husband are. She uses her alone time as a way to fuck another man behind Percy's back.
Later in the series, the Spencer household is shown with a then-modern house phone. While this can be considered a case of Technology Marches On, Percy generally has enough money to buy booze and smokes on a regular basis, so he might have used some of the money to buy a phone.
In "Sore Throats", Anastasia blasts Percy with water from a hose, resulting in his fork getting lodged inside his stomach. While Anastasia laughs it off, getting a metal fork stuck inside of you would damage your insides.
At the beginning of "Quest", Kevin scares Percy with a naked picture of Anastasia, which causes him to have a heart attack (stroke). Percy begs Kevin to give him the puke bucket, and Kevin tells his dad that he will only call for help if he remembered or started caring. Given that Percy also doesn't appear in the episode beyond this point, it's possible Kevin left him to die.
In "Jacked In", Shawna pulls the plug on the virtual reality machine Kevin and Percy are connected to, which gives them brain damage (among other things the narrator describes). Although they do survive, they could've easily died.
In "Mother's Little Helper", the narrator mentions that Kevin would never take a life, despite the fact that Kevin had taken multiple lives prior to this.
How do the Spencers pay for the house if they are poor? Furthermore, "Blow Job" and "Demolition Derby" (among others) have the house being destroyed by a hurricane in the former and by Anastasia with a chainsaw in the latter. How do they pay to get it rebuilt if it gets destroyed ever so often?
If Greg Lawrence died from a insulin shot in "Merry Christmas, Asshole!", why does he reappear in "Air Show" alive and well?
In "Homeward Bound", Allen somehow is able to build a robot despite the fact that he and Kevin are stranded on a island. Keep in mind this occurs before he and Kevin discover Hughtopia.
In "Legitimate Claims", Percy is shown to have illegitimate children despite none of the preceding episodes even mentioning this fact.
In "The Heroic Spencers", the Spencers attempt to get a reward for stopping a robbery after they left the bank. Why didn't they just ask for the reward while they were still at the bank?
In "The Art of Pornman", no one takes note of the fact that Kevin, a minor, attends the porn studio tour.
