The moment when Billy grabs Max's wrist was not scripted; Sadie Sink and Dacre Montgomery worked that out on the day of shooting to increase the tension between the two characters.
True Sight is a Dungeons and Dragons spell that allows the caster of the spell to see invisible, displaced, and astral objects. The subject could see into the Ethereal Plane and other coexistent planes, the Upside Down world in Will's (Noah Schnapp) case. The spell could tell a creature's alignment and intentions by looking at them which may be why the first views Will has of the creature show it in a dark cloud with red tones, denoting the evil intentions of the creature. The spell was first introduced for the Original Dungeons and Dragons as part of the Illusionist spell list in Dragon Magazine #1.
The episodes title name "Will the Wise" refers to the name of the wizard character played by Will Byers (Noah Schnapp) in the boys' Dungeons & Dragons campaigns.
This episode takes place from November 1 to November 2, 1984.
Bob (Sean Astin) does not appear. This is the first time one of the main cast is credited but does not appear.