Many of Egon Spengler's favourite snacks make a reappearance in the movie, such as Cheese-It crackers, Crunch, and the Twinkie.
The Revelation 6:12 prophecy written on the junk in front of the farmhouse is the same Bible verse Ray quotes in Ghostbusters (1984). When Ray is seen again, he has the verse tattooed on his arm. The verse says: "I watched as he opened the sixth seal. There was a great earthquake. The sun turned black like sackcloth made of goat hair, the whole moon turned blood red."
Paul Rudd announced via social media that he would be joining the cast while standing in front of Hook and Ladder 8 (Ghostbusters HQ) in New York City.
Bill Murray had been reluctant to reprise his role as Peter Venkman for decades, though he did appear in the video game Ghostbusters: The Video Game (2009). He said in an interview that he finally chose to return because, "The script is good. It's got lots of emotion in it. It's got lots of family in it, with lines that are really interesting. It's gonna work."
Tracy Letts: playing the shopkeeper who tells Callie (Carrie Coon) more about the Dirt Farm. Letts is Coon's real-life husband.