In the Halloween episode 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).)
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.