From episode 20 and onward, Betty often displays an inability to correctly pronounce the words "architect" and "secretary". In prior episodes, she never has any difficulty in saying those words properly.
At one point during the show's first season, Martin states that the street address of the Kelly house is 33 Jacaranda Avenue. In the series finale, Greg mentions that the address is 26 Jacaranda Avenue.
When Rachael Beck debuts in season five as Sam, Martin recognizes her as the daughter of his older brother, Mark. In season one, Martin had reminded his mother that he was an only child and did not have a brother.