Cathy Moriarty, who plays Wendy's aunt Gert in this film, originally played the role of villainess Carrigan in Casper (1995).
Both Casper: A Spirited Beginning (1997) and this film are not set in the events of Casper (1995), and are considered non-canon.
Before Desmond creates the Mystic Abyss, he says, "From the halls of Kugaluma to the shores of Xanadee..." This is taken from the first line of the US Marines Hymn: "From the halls of Montezuma to the shores of Tripoli..."