Elizabeth Olsen requested that her official Scarlet Witch costume be high collared, as she was uncomfortable with the low cut, cleavage baring costumes she had worn in previous MCU films.
Agatha tells Wanda that there's an entire chapter dedicated to her in the Darkhold. The Darkhold is the book of the damned that debuted in the MCU on the series Agents of S.H.I.E.L.D. (2013). It was the cause of all the misfortunes during season four and was ultimately taken back to hell by Ghost Rider. The Darkhold then appeared again in the third season of Marvel's Runaways (2017), where it was in the possession of the magic user Morgan le Faye. This Darkhold; however, doesn't appear to be the same book-the previous Darkhold featured an ambigram title on the cover-potentially beginning the de-canonization of the non-Disney+ TV series.
It was previously noted that starting with episode 2, Don't Touch That Dial (2021), the house used for the exterior shots of Wanda and Vision's home is the same house used for exterior shots of the Griswold family house in National Lampoon's Christmas Vacation (1989). As an additional homage to that movie, during one of Vision's fight scenes, he tosses his opponent into an RV. If you freeze the frame, you can see from the top and back/side views that it is a dilapidated RV resembling Cousin Eddie's vehicle from National Lampoon's Christmas Vacation (1989).
The movie showing at the modern-day Westview Theater is 'Tannhauser Gate.' Tannhauser Gate is mentioned by replicant Roy Batty (Rutger Hauer) in his 'Tears in the Rain' monologue in the movie Blade Runner (1982).
The car into the window of Dot's house is a nod to the Lethal Weapon series where damage constantly happened to the house. Both houses are portrayed by the same house.