Prior to drinking the hallucinogenic mushroom tea, The Deep says the last time he did mushrooms was at a Goo Goo Dolls concert. In his next scene (when the mushrooms are kicking in), he is listening to "Iris" by the Goo Goo Dolls.
Keeping in theme with his character, Mother's Milk wears a Boogie Down Productions t-shirt, an influential rap group from the 80's and early 90's.
Kenji is wearing a Spuds MacKenzie shirt, a Bull Terrier who was used in Bud Lite advertisements in the 1980s.
Butcher awakens at a Tony Cicero's, presumably a message from Homelander that he has figured out that Butcher and the boys murdered Translucent at one back in season 1.
After drinking the hallucinogenic tea, The Deep listens to "Iris" by the Goo Goo Dolls which is the title track from the soundtrack to "City of Angels" starring Meg Ryan who is Jack Quaid's mother.