Courage's dialogue decreased after the first season. This is because the creators at Cartoon Network thought Courage "talked too much" and wanted his dialogue cut short.
Lionel Wilson (Eustace) quit halfway through the series due to illness and was replaced by Arthur Anderson.
The names Muriel and Eustace are taken from the middle names of Chandler Bing and Ross Geller of Friends (1994).
The original season 2 finale The Tower of Dr. Zalost (2001) didn't air until after the season 3 premiere Muriel Meets Her Match/Courage vs. Mecha-Courage (2002) aired.