Finn hanging over the Lich's well of power by one hand is similar to how Obi-Wan Kenobi was hanging over a pit while fighting Darth Maul in Star Wars: Episode I - The Phantom Menace.
Finn points out he and Sweet P's similarity in having bad biological fathers and nice adoptive parents, making a reference to Martin Mertens, Joshua and Margaret.
Fern reveals the ability to transform his body to be more like Finn, which he uses in " Three Buckets.".
This references " Mortal Folly"/" Mortal Recoil," " The Lich"/" Finn the Human"/" Jake the Dog," " Wake Up"/" Escape from the Citadel," and " Crossover."
Finn states that this is the fifth time he has fought the Lich.
This episode reveals that during "Crossover," after Finn's grass arm chopped off Farmworld Lich's hand and Jake pushed into the multiverse portal, it landed on BMO and ran out of the Tree Fort because the Lich's spirit is still within it.
Flashbacks from the Elements miniseries are shown as Fern recalls himself not protecting Ooo while Finn and Jake were away at sea.
Finn first assumes that Sweet P was referring to LSP when he says 'Monster.' This likely a reference to LSP's monster persona that was seen in the episode " The Monster," where she was terrorizing a village for their food.
The return of the Lich was foreshadowed in " Orb.".
The Lich calls himself "the last scholar of GOLB" who is first shown in " Puhoy", referenced in " You Forgot Your Floaties and appears in the final episode " Come Along With Me.".
The Lich's well of power in the ruins of a subway station is seen for the first time since "Mortal Folly.".
This is likely due to the Grass Demon that resides within Fern.
When Finn and Fern cling onto the screaming, running Sweet P, Fern's legs are spread out to the sides, like a spider's would be, whereas Finn's are tucked in, human-style.
The ceiling tile area where the Lich's shadow appears is right above the spot where Finn defeated the Lich in " Mortal Folly." (The ceiling tiles can be seen in that episode.).
The nails on the Farmworld Lich's hand are a lot more visible than they were in " Crossover.".
Farmworld Finn (flashback, non-speaking).
Princess Bubblegum (flashback, non-speaking).
He wonders about his identity, and thinks that things would be different if he was the only Finn. Fern watches the two of them, and stews in his uselessness. They meet up with Fern, and go back towards Treetrunks' house. Finn asks what happened to Fern, and Sweet P simply replies that he knocked him out. However, Sweet P declares that he is not going to be a part of the Lich, and destroys the hand. Sweet P appears, and Finn fears the worst. The hand, speaking for the Lich, says that Sweet P is part of him, and will eventually be swayed to come to his side. The hand ends up knocking Finn into a pit. He asks Fern to guard Sweet P, and chases the hand down. Sweet P says that the voice at night belongs to the Lich, and Finn decides to go after the hand. He attacks the hand, but it repels both him and Fern. In the evening, Finn wakes up to see the Lich's hand whispering to Sweet P. Sweet P claims that a voice is telling him that he is terrible when he tries to sleep at night, and the two decide to watch over him at night. Sweet P then comes crashing through the woods in tears, and Fern has to wrap him up in leaves to cheer him up. Finn tries to cheer him up, to only of a little avail. Fern expresses his frustration, leftover from being unable to protect Ooo from the Elementals. Plotįinn and Fern are fishing, but while Finn catches a golden fish, Fern catches a carnivorous one.