There were originally supposed to be eighteen episodes.
All of the names that Gregory (Collin Dean) names his lucky frog (Jack Jones) are: Kitty, Wirt, Wirt, Jr., George Washington, Mr. President, Benjamin Franklin, Dr. Cucumber, Greg, Jr., Skipper, Ronald, and Jason Funderberker.
After the opening titles in each episode, a distant train horn can be heard. The boys meet this train in episode nine, "Chapter 9: Into the Unknown".
In episode two, "Chapter 2: Hard Times at the Huskin' Bee", Gregory (Collin Dean), Wirt (Elijah Wood), and Beatrice (Melanie Lynskey) pass through Pottsfield, a town full of skeletons. This is a portmanteau of Potter's Field, a term for a graveyard for people who can not afford to buy a burial plot.
The phase of the moon in the show was meant to match up with the phase of the moon on the night each episode originally aired.