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.
Clara Peller reprises her role in a parody of Wendy's "Where's the Beef?" advertisements, asking instead, "Where's the Stuff?"
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.
Chocolate Chip Charlie was inspired by Famous Amos cookies.
The company Effects Associated were hired by Larry Cohen to supply some of the special effects shots. When the shots were delivered, Cohen was not satisfied with shots of exploding factory buildings and paid only half (c. $8,000) of the agreed price for those shots. Effects Associated brought an action against Cohen in court to claim full compensation, but also because the parties had no written copyright agreement regarding the use of the shots. The trial court decided in favor of Cohen, ruling that there was an "implied agreement" for the non-exclusive use of the shots in the film. The Court of Appeals for the Ninth Circuit confirmed the ruling, and confirmed that Effects Associated still retained the copyright for use outside of The Stuff.