The book that "Arthur's Family Vacation" was adapted from begins on Arthur's last day of school in Mr. Ratburn's 3rd grade class. In this TV adaptation, it is a flashback event set during the summertime between the end of Arthur's 2nd grade school year and beginning of his 3rd grade school year.
The first appearance of Arthur's maternal grandfather, Grandpa Dave alongside that he appears in the TV series' opening sequence featuring the Read Family. While he appears in the opening sequence, he is a recurring character whom only appears in a few episodes in the series and lives outside Elwood City.