As Wirt sleeps, he dreams of exactly how Greg and he ended up in the Unknown.
Tropes:
- Arboreal Abode: Despite the lot of them living in a tree, Beatrice's mother still refers to their home's entrance as a 'doorstep'.
- Double-Meaning Title: "Into the Unknown" represents Wirt's insecurities on his path to give Sarah his mix-tape but it also tells about how Wirt and Greg went over the garden wall and into the Unknown.
- Foreshadowing: The below mentioned Freeze-Frame Bonus hints at the Unknown being some kind of afterlife.
- Freeze-Frame Bonus: One of the headstones in the graveyard reads Quincy Endicott.
- The '80s: The real age when Wirt and Greg lived appears to be the 1980s or later.
- Good Parents: Beatrice's mother doesn't care that Beatrice got her and the family turned into bluebirds, she just wants to know where her daughter is. She also nurses Wirt back to health.
- In the Style of: The rock song that opens the episode is a pastiche of the T. Rex song "Ballrooms of Mars."
- Jerkass Realization: After spending the whole flashback (and several previous episodes) trying to blame Greg for the messes caused by his own indecision and insecurity, Wirt seems to realize he's the one to blame for him and his brother ending up in the Unknown.Beatrice's Mother: You'll be no good to your brother dead!
Wirt: (sadly) I was never any good to him alive either. - Police Are Useless: The police spend most of the episode jokingly calling out to kids they're under arrest. When they do this in the graveyard, Wirt panics and takes Greg with him up a tree. The police, instead of calmly following them on foot, chase the kids in the car while telling them to come back.
- The Reveal:
- Wirt and Greg are revealed to be kids from the 1980s who came to the Unknown by almost drowning. The Unknown itself is revealed to be either an afterlife realm or a dream. (It's never made entirely clear).
- Jason Funderberker is revealed to not be the cool jock and competitor for Sara's affections that Wirt had been describing him as, but is instead a bigger dork than Wirt is and Sara clearly has no interest in him.
- Title Drop: Wirt says the chapter title word for word as he sets out to give his tape to Sara.
- Tomato Surprise: Wirt and Greg aren't wearing those clothes because they're from the "olden times", they're modern-day kids wearing Halloween costumes. This was subtly hinted at throughout the series by how Wirt and Greg frequently made comments that seem anachronistic (like Wirt claiming to be in high school or asking the Pottsfield people if they have a phone), which most people wouldn't think twice about.
- Unwitting Instigator of Doom: If the police didn't decide to joke around with Wirt and Greg then the two wouldn't have gone over the garden wall and drown in the lake.
- Wham Episode: Wirt and Greg are from the modern day world and wound up in the Unknown after falling unconscious into a river.
- Whole Episode Flashback: The whole episode is a flashback to Wirt and Greg entering the Unknown, which turns out to have (possibly) been Wirt dreaming as he was unconscious.
