The headlines in the father's newspaper ("Man's Face Gets Stuck" and "Boy Digs to China") refer to the common childhood beliefs that one can dig to China and that if one makes a funny face, it can get stuck that way.
Although this episodes aired in 2002, they were actually made in 2001 according to the credits.
Robot Jones from Whatever Happened to Robot Jones? is seen as a toy on a bookshelf on one scene where Dexter walks over to the window and looks outside.
The concept of Dexter having a excuses for P.E. goes way back in season 1 episode "Dexter Dodgeball" where he tried to give the gym teacher a excuses to let him miss gym forever, only to learn that the regular gym teacher is sick and new sub ripped up the excuses, forcing him to stay in gym.
This was the first episode to air after the short Dexter's Laboratory: Chicken Scratch (2001) (which was originally released as a featurette for The Powerpuff Girls Movie (2002), two days before the episode), was aired as the 12th episode from the show's next season in November 2003. However, two more episodes from the third season, "Scare Tactics/A Mom Cartoon/My Dad vs. Your Dad" and "Jeepers, Creepers, Where Is Peepers?/Go, Dexter Family, Go! are last two that aired on the following week before the show's next season was aired on November 2002. (A rerun of the 12th episode of the third season was aired on September 20, designated as the finale after the 13th episode.)