The argument over whether or not the ghosts are Pirate Ghosts or Ghost Pirates was an actual debate between Korn, Trey Parker and Matt Stone.
The "Alabama Man" action figure from Chinpokomon (1999) can be seen in Cartman's catalog. Chinpokomon was produced earlier, but was broadcast later. The Mr. Hankey Construction Set from Mr. Hankey, the Christmas Poo (1997) also makes an appearance.
When the boys are digging up Kyle's grandma, next to her headstone, two of the other headstones are clearly written on. The one on the right says "Kenny 2000" and the one on the left says "Kenny 1999."
Comedy Central wanted the episode to feature the Korn song "Falling Away From Me" on the soundtrack, but Trey Parker and Matt Stone said that they weren't interested in a gimmick like that. The extended Scooby-Doo parody with Korn as Mystery Inc., then playing the song live at the end, was them meeting the network halfway. They both insisted in the commentary that they will "never do that again."
In one scene, Korn can briefly be heard playing a piece from Skyler Morse's song "Shelly, Shelly" from Cat Orgy (1999).