According to audio commentary on the 2000 Anchor Bay DVD, the scene in the motel where the Stuff comes out of the mattress and pillows and attacks the man on the wall and ceiling was shot in a room that could turn upside down, allowing the Stuff to move up and down the wall. It was exactly the same room used in A Nightmare on Elm Street (1984) when Johnny Depp's character Glen is sucked into his bed and his blood is regurgitated back out onto the ceiling.
According to Larry Cohen himself, in some scenes in which the Stuff chases characters, a foam made of blended fish bones was used. It stank so much that, as soon as the shots were done, the actors ran to a river in order to bathe and get rid of the stench.
According to the audio commentary on the 2000 Anchor Bay DVD, some of the substance props or stand-ins for the real Stuff used in the movie included lots of Häagen Däzs ice-cream, yogurt, and, for one scene involving an enormous avalanche-like effect of Stuff crashing though a wall, fire-extinguishing foam. Other shots, such as the ones of the giant lake of Stuff required superimposed images and animation.
Garrett Morris was asked about this film when he participated in AV Club's "Random Roles" interview series. He said the production was "crazy", and when the interviewer noted Larry Cohen's history as "a character' and asked Morris what he was like, Morris said that "I was taught growing up that if you don't have something nice to say about someone, don't say anything at all" with no further comment about Cohen.
Michael Moriarty (David 'Mo' Rutherford) and Paul Sorvino (Colonel Malcolm Grommett Spears) will go on to appear in 31 episodes of Law & Order together from 1991 to 1992, respectively as "Executive A.D.A. Ben Stone" and "Sergeant Phil Cerreta".
David 'Mo' Rutherford tells 'Chocolate Chip' Charlie W. Hobbs to contact agent Frank Herbert from the FBI. Frank Herbert was an American science fiction writer best known for the novel Dune and its five sequels.