The school bus reads "Heimlich County School District." But in later seasons the name has been changed to "Arlen Independent School District."
Tom Landry Middle School is stated to be in the "Heimlich County School District" according to the bus Bobby rides. But in later seasons the buses list it as the "Arlen Independent School District." (This is most likely a continuity oversight, however, it is possible Arlen schools split off from the rest of Heimlich County to form a separate school district at some point.)
When Hank looks at the calendar in the boiler room, Mother's Day is shown to be on the third Sunday of May, rather than the second Sunday.
Hank looks through ADD medicine leaflets and goes through the one that the doctor gave him for information about ADD, not about medicine.