Chekhov's Gun/Table Top Gaming

• In a game module in the Star Wars RPG, a couple of Squib merchants arguing with another group of merchants near the entrance to a ruined Jedi Academy have a burned out lightsaber for sale. This lightsaber allows you to interact with an important NPC later on, finding out some key info.
• Many of the Fighting Fantasy gamebooks published in the United Kingdom have the reader collect all sorts of strange odds and ends, most of which seem to have no possible justification for the adventurer taking them along. Naturally, those seemingly useless items end up being just what the reader needs to get him- or herself out of trouble, or otherwise make an enemy easier to defeat.