In an interview with ScreenTime, director Dan Trachtenberg revealed that he originally intended to direct the third episode of the fifth season of "Stranger Things," but was forced to decline due to scheduling conflicts with the production of "Predator: Planet of Death."
To compensate for his absence, Trachtenberg came up with a countermove — he invited the Duffer brothers to participate in his film.
Matt and Ross Duffer agreed, although, according to Trachtenberg, they were a little nervous — after all, they are not actors. Now, it is their voice that speaks for the Yautja ship, the alien race of hunters known popularly as "Predators."
According to Trachtenberg, the brothers' cameo became a way for them to "work together in a friendly way," despite scheduling differences and being busy on different projects.