Foster's Home for Imaginary Friends: Luz's bad hair photo references Mac's friend Goo Goo Goo Ga Ga.
Gravity Falls: The episode: Dreamscaperers is referenced throughout the episode as both episodes involve individuals entering picture frames/doors that manifest movie-like viewings of memories.
Super Mario 64: Luz putting her hand in a painting and then her head is what Mario did in the classic Nintendo 64 game.
Eternal Sunshine of the Spotless Mind: Lake Lacuna references Lacuna, Inc., the company that offers to erase unwanted memories.
Psychonauts: The concept of entering someone's mind and trying to fix it/exploring it is a common theme in Psychonauts, not to mention discovering memories and a world based on anybody's mind and meeting their inner mind-selves.
Skara's nose disappears in a single frame during Boscha's imitation of Willow.
When the fire monster first appears behind Amity and Luz in the beach memory, its frame is transposed above Luz's head.
Although Skara speaks in the episode, her voice actress is not listed in the credits.
In Southeast Asia, Willow's dads are blurred out.
Christmas, or an analog of it, is celebrated on the Boiling Isles.
Skara is officially named in this episode.
Mr. and Mrs. Blight make their first appearance, albeit as silhouettes.
Amity visits the Owl House for the first time in this episode.
The secret code is translated to "And"
This is the first episode where Luz is not seen wearing her signature outfit besides the intro.
This is the first episode to air on the same date as it's prior episode.
It is seen that Willow has two dads.
It is shown that Amity used to have brown hair as a child.
It is revealed that the reason Amity and Willow stopped being friends is because Amity's parents forced her to.
There's levels to me kid, levels I say!
Must I turn to forbidden sources?
Willow, you were never too weak to be my friend. I was too weak to be yours.
I remember what you did too. What you did in there. I can’t say we’re friends, but it’s a start.