There is always a person in the school wearing a big yellow caterpillar costume, but nobody knows who is in the costume.
Along with "The Thundermans" (2013), this was the first non-spinoff from Nick to have a crossover.
Ernie Hudson, best-known for playing Winston Zeddemore in the "Ghostbusters" films, makes a guest appearance as Ray's father, who is also a ghost.
How the Prestons died is never stated. One popular theory is that Ray, the dad, was divorcing the mother and engaged in a custody battle, so he killed the kids--hence why the mother's not there. Another theory is that Miles was the one who killed the family and himself because he loves the idea of the Prestons and the Hathaways being a family.