Danny is seen in a healing tube in his underwear. This is a reference to "Star Wars: The Empire Strikes Back" where Luke Skywalker is seen in a similar healing tube. Luke is played by Mark Hamill, who does the voice of Undergrowth in this episode.
Introduced Ghost Powers: Cryokinesis, the power of cold.
The green clothing Sam wears under Undergrowth's mind control the first time is reminiscent of Poison Ivy, a Batman villain.
The first time Grey Delisle (Sam Manson) & Guest Voice Mark Hamill (Undergrowth) work together. They work together again, in another Nickelodeon TV show, in Avatar: The Last Airbender, as Firelord Ozai & Princess Azula (respectively)
Nickelodeon aired this episode on TV out of order. It was aired before any of the other episodes of Season 3, despite it really being the sixth episode of Season 3. This caused some confusion due to Frostbite's presence (who was supposed to have been introduced in "Infinite Realms") and Vlad being mayor of Amity Park (which was supposed to have happened in "Eye for an Eye," the actual Season 3 premiere).