Finn and Fern's carefree visit to some old ruins turns disastrous.
Fern invites Finn to some quality time in some ancient ruins, as BMO and Jake take a trip to the Music Kingdom. They end up playing in a field, but Fern says that it is boring. He wants the thrill of victory, not monotony. When Finn ends up beating Fern in rock-paper-scissors, and Fern complains about how nothing is fair to him.
They go through a door in a cliff, and into a ziggurat temple. While inside, Finn says he is happy that they both have a love of adventure in common, and that it feels like they are real brothers. Fern gives him a blank stare, and when Finn walks inside the main room, he locks him in. Fern declares that he is going to replace Finn, and leaves him inside the temple. As Finn messes with his robotic arm, he discovers a hidden microphone, with a message from Princess Bubblegum. He realizes that his robotic arm has multiple features, including a rock smasher and a weed whacker.
He charges at Fern, and the two end up fighting each other. Fern says that Finn has been Finn long enough and that it is time for someone else to have a shot. Fern's eyes suddenly begin to glow, and Finn wonders what Fern really is. They come to a stalemate, and Finn sadly says that it does not have to be like this, but Fern is resolute. The weed whacker function activates, and Fern is torn to shreds.
Finn returns home, despondent and traumatized. A stranger gathers up Fern's remains and vanishes into the distance.
- This episode portrays an example of the "bad twin" trope, where one of the two becomes the sworn enemy of the other. This is seen in books such as John Steinbeck's East of Eden and is very common in cheap detective novels and soap operas.
- This episode portrayed the concept of a clone/twin of the protagonist turning on them in a battle to the death, the concept is also shown in series as Star Trek: The Original Series, Rick and Morty, Regular Show, Star Wars, and several others.
- When BMO, Fern (disguised as Finn), and NEPTR all claim to have broken Jake's vuvuzela, this was reminiscent of the final scene in the movie Spartacus. In the movie the defeated slaves all claim to be Spartacus and it uses this event as a metaphor for standing up to Sen. Joseph McCarthy's House Un-American Activities Committee.
- This reference is also in the episode, "The Thin Yellow Line."
- The vuvuzela is the national symbol of South African soccer. It became infamous during the 2010 FIFA World Cup in South Africa when the incessant sound of fans blowing them were heard over television sets across the world.
- Fern discovered his abilities to disguise as others in the previous episode, "Whispers."
- Finn says he is very sensitive to being abandoned. This may be due to his past family history.
- In a hologram, Princess Bubblegum mentions the events of "Reboot" / "Two Swords" where Finn lost his arm again and his fight with Susan.
- This and the previous episode show that Finn and Sweet P had fought their demons since in this episode, Finn weed whacked Fern and the previous episode, Sweet P is shown to kill of the farmworld Lich. Both of which has been haunting/consuming each other since Season 5 (Finn & The Grass Sword), and Season 6 (Sweet P having Lich nightmares). This makes both this episode and the previous episode connected in some ways.
- Finn's prosthetic arm is actually more than meets the eye. It can be used as several power tools and even a weapon, and has a microphone and holoscreen.
- With the "weed-whacker" mode on his arm, Finn kills Fern by accidentally turning on "Fatality" mode on the weed whacker and cutting him in the chest resulting in him bursting him into pieces of grass.
- However at the end of the episode Fern's remains are seen and his eyeball moves. This may imply that in some way Fern is alive.
- The room in which Fern trapped Finn is very similar to the inside of the Finn Sword: it's an empty space with just a small amount of food and a chair.
- This episode is the season 8 finale. 
- Despite this it is considered the season 9 finale on cartoonnetwork.com.
- This episode was released early on the Cartoon Network app on July 14, 2017.
- The list of abilities of Finn's arm changes order twice. Once after Finn says "Huh." and then when the view zooms into the Weed Whacker option.
- When Finn is being held down by Fern and the grass sword, his shirt isn't rolled up in one shot.
- ↑ 1.0 1.1 http://tvlistings.zap2it.com/tv/adventure-time-three-buckets/EP012462651638?aid=zap2it
- ↑ http://kingofooo.tumblr.com/post/162720736549/adventure-time-returns-on-monday-july-17th-five
- ↑ https://kametsu.com/topic/57130-cartoon-network-unofficial-previews/?do=findComment&comment=558043
- ↑ https://ask.fm/MrMuto/answers/143415325128