In Foster's Home for Imaginary Friends: Bloooo (2004), where Bloo becomes ill and turns white, Wilt, Eduardo, and Coco think of ways to capture the ghost while mentioning several movie titles pertaining to ghosts. (Coco says 'Co coco!' as the song 'Ghostbusters!' goes, and Wilt talks about the Star Wars: Episode I - The Phantom Menace (1999).)
This is the first Cartoon Network Studios show done in Macromedia Flash, enabling a small staff to produce an entire episode in-house.
The character Mr. Herriman is loosely based on Peter Cushing's portrayal as Dr. Abner Perry in At the Earth's Core (1976).
Creator Craig McCracken got the idea for the show when he and the show's co-developer Lauren Faust adopted 2 chocolate lab dogs.
The whereabouts of Mac's father is never mentioned and it is assumed that Mac's mother is raising Mac and Terrence as a single parent. The only slight reference to Mac's father is when Bloo narrates Mac's school by opening Macs scene with "A boy with no father..." But Mac quickly scorns him implying it to be a sensitive subject.
In the TV movie "House of Bloo's" (the pilot), an Eduardo doll can be seen in the back of Terrence's room.