Brain says that he spent his summer teaching summer school, but schools wouldn't hire students, elementary school students at that, to teach other students.
D.W. says that Kate spoke her first word in this episode, but she learned to say "Brain" in "The Perfect Brother."
Arthur: Huh? What's going on? D.W., what are you doing?
D.W.: I'm making sure you're not lost. Arthur, you scared me. You'[d better promise never to get lost again.
Arthur: Okay, I won't.
D.W.: Do you promise?
D.W.: Cross your heart?
Arthur: (yawning, about to fall asleep) Cross my heart.
Fern: I went to poetry camp, I was the poetry champ. This ribbon on my chest proves that I'm the best. And now I can't stop all these rhymes.
I must have tried a thousand times!
Bus Driver: (in fantasy sequence) Where do you think you're going?
Old Arthur: Please, can't I just leave? I've been on this bus for forty years.
Bus Driver: Not until you pay your fare.
Old Arthur: But I didn't bring any money with me. It's in my other pants.
Bus Driver: Guess you should have thought of that before you got on the bus, old man! (He lets loose with an evil laugh.)
The design of the alien 'space bus' in the episode "Lost!" was heavily influenced by the Eagle ships in the 70's SF show, Space:1999.
"Lost!" is based on one of the Arthur books with the same plot.