Grief and personal loss fill in gaps in the Marvel Cinematic Universe in Friday’s episode of “WandaVision,” the eighth of the season and, at 48 minutes long, the longest to date. Titled “Previously On,” it is the installment that most clearly ties the show’s events to other Marvel movies and TV shows, like “Avengers: Age of Ultron” and “Agents of S.H.I.E.L.D.”

At the same time, it is an origin story for the disorienting sitcom world that much of “WandaVision” has inhabited. Through a series of extended flashbacks, the tortured superheroine Wanda Maximoff (Elizabeth Olsen) relives the traumatizing events that led her to transform the contemporary New Jersey suburb of Westview into the Hex, a TV-addled neighborhood that she has surrounded with a mysterious energy dome and cut off from the outside world.

More often than not, Wanda’s flashbacks suggest that she is consistently motivated by the death of her loved ones, especially the loss of her parents, Iryna and Olek Maximoff (Ilana Kohanchi and Daniyar) and her brother, Pietro (Evan Peters). “Previously On” also hints at what motivates Wanda’s witchy rival, Agatha Harkness (Kathryn Hahn), whose antagonistic behavior in “WandaVision” contrasts with her cryptic but benign personality from earlier Marvel comics.

Here are some of the key comic book and movie references in this week’s “WandaVision” episode. Major spoilers follow.

Agatha Harkness’s Salem Witch Trials

The episode begins by flashing back to Salem, Mass., in 1693, when Agatha was confronted and almost burned at the stake by a coven of witches. Evanora (Kate Forbes), the group’s leader and Agatha’s mother, accuses Hahn’s villainess of betraying her fellow spellcasters. This flashback parallels the beginning of Vision and the Scarlet Witch No. 3, when the aggrieved members of Salem’s Seven, Agatha’s coven, successfully burn her alive. (She had previously revealed to the Fantastic Four the location of New Salem, a secretive witch community, in Fantastic Four Annual No. 14.)

Beyond that association, Agatha Harkness is otherwise distinct from how she’s depicted in the comics: She casts a spell on and destroys her mother and her fellow witches, a jarring change from the comics’ general narrative that also immediately announces this week’s focus on revisionist history.

Wanda’s Parents and the Unexploded Bomb

Wanda first revisits the death of her parents, Iryna and Olek, which happens when the American military destroys their Sokovia hometown, Novi Grad, with bombs manufactured by Stark Industries. Wanda’s parents were first mentioned in “Avengers: Age of Ultron,” and in that movie she and her brother, Pietro (played in that movie by Aaron Taylor-Johnson), blame the industrialist turned superhero Tony “Iron Man” Stark (Robert Downey Jr.) for their parents’ death, which leads them to ally with the megalomaniacal robot Ultron (James Spader).

Wanda also relives another moment that is mentioned, but not shown, in “Avengers: Age of Ultron”: During the bombing of Novi Grad, she and her brother were pinned under rubble for two days, waiting for one of Stark’s bombs to detonate. In “Previously On,” we learn that the bomb never exploded because Wanda defused it with her “chaos magic” powers. This unexploded bomb resembles the drone missile that was sent into the Hex by the superhero-regulating government agency S.W.O.R.D. (or, Sentient Weapon Observation and Response Department) in “On a Very Special Episode …,” the fifth episode of “WandaVision.”

HYDRA, the Mind Stone and Loki’s Scepter

After revisiting her childhood Novi Grad home, Wanda remembers when she, as an adult, volunteered to be a test subject for deadly experiments that were conducted by HYDRA, a Nazi-like terrorist organization that served as the main villains in most of Marvel’s recent movies as well as the “Agents of S.H.I.E.L.D.” TV series.

Wanda recalls and expands on the post-credits scene from “Captain America: The Winter Soldier,” when she and Pietro were imprisoned by the HYDRA leader, Baron Wolfgang von Strucker. (Strucker’s name might ring a bell with “WandaVision” fans: There’s an ad for Strücker brand wristwatches in the show’s second episode.)

In the comic book tie-in “Avengers: Age of Ultron Prelude — This Scepter’d Isle,” Strucker and his men explain how, just before the “Captain America: The Winter Soldier” post-credits scene, they gave the Maximoff twins superpowers using a magical scepter that they swiped from the Norse trickster god Loki (played in the films by Tom Hiddleston).

Loki’s staff also connects Wanda with her android husband, the Vision (Paul Bettany), since the scepter’s reality-altering powers come from the same Mind Stone that Ultron used to give life to the Vision in “Avengers: Age of Ultron.” This week, Agatha suggests that the Mind Stone significantly “amplified” Wanda’s psychic powers, which would have “otherwise died on the vine.”

The Snap: S.W.O.R.D. Headquarters

When Wanda remembers retrieving the Vision’s body from S.W.O.R.D. headquarters, TV news tickers in the lobby announce “families reunite” and “[celebrations] for the returned.” This alludes to a cataclysmic event from “Avengers: Infinity War” known as “The Snap.” That was when the philosophically inclined alien warlord Thanos (Josh Brolin) halved the world’s population simply by donning his all-powerful Infinity Gauntlet and snapping his fingers.

This means Wanda took the Vision’s body some time after “Avengers: Endgame,” which was when Wanda and her teammates undid the Snap’s effects.

The Vision’s Vibranium Body

During Wanda’s visit to S.W.O.R.D. headquarters, the S.W.O.R.D. director, Tyler Hayward (Josh Stamberg), explains that the Vision’s body must be destroyed because he is “one of the most sophisticated sentient weapons ever made.” That’s because the Vision’s body is made of Vibranium, an alien element that crash-landed in the African nation Wakanda (the main setting of “Black Panther”) during a meteor shower and was subsequently developed into an indestructible metal — it is used in some of the Marvel world’s most sophisticated and highly sought after technology and weaponry, including Captain America’s shield. Ultron created the Vision’s body in “Avengers: Age of Ultron” using Vibranium stolen by the deranged and questionably accented South African arms dealer Ulysses Klaue (Andy Serkis).

The Snap: Lagos

Eagle-eyed viewers will also note that Thanos’s fateful snap is subtly referenced twice this week. The first time is on a Westview mural advertising something called “Snap,” which can be seen briefly after Wanda uses her superpowers to transform the town into a sitcom fantasy. That same mural also mentions the Nigerian city Lagos, a reference to a scene from “Captain America: Civil War” when Wanda accidentally destroyed a building full of Wakandan civilians while trying to disarm a bomb.

The Vision’s New Look

The real Vision comes back to life during a mid-credits scene this week, but he doesn’t look the way he used to. He was destroyed twice in “Avengers: Infinity War”: first by Wanda, who was trying to stop Thanos from taking the Vision’s Mind Stone, and then by Thanos, who later used the Infinity Gauntlet to travel back in time and steal the stone.

Outside of Westview, Hayward reanimates Vision’s body using the chaos magic that rubbed off on the drone missile back in Episode 5. Comics fans might recognize the Vision’s new off-white costume from West Coast Avengers No. 45, when an international team of spies deleted the android’s old personality and redesigned him after he, under the influence of the evil supercomputer I.S.A.A.C., tried to take over the world.