These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
EIGHT!Explanation The demo of the 2013 HD remake features a button in place of the actual The Stanley Parable demo that has a red number eight painted on it and pressing it causes a voice to shout out "EIGHT!" while the number lights up on several tiny monitors behind it. The Narrator pleads with the player that this is not the actual game and demands him to leave the room, becoming increasingly desperate if the player remains and repeatedly presses the button.
OH, DID U GET THE BROOM CLOSET ENDING? THEB ROOM CLOSET ENDING WAS MY FAVRITE!1 XD Explanation If you spend too much time loitering in the broom closet, the Narrator asks if you're holding out for another ending, and says there isn't one. He then snarks that you're probably stupid enough to think waiting in the closet is the ending, and you'll go on the internet afterwards and say "OH, DID U GET THE BROOM CLOSET ENDING? THEB ROOM CLOSET ENDING WAS MY FAVRITE!1 XD"
That One Achievement: The HD version goes to town on parodying this. The top three "impossible" achievements require you to spend an entire Tuesday playing the game, to not play the game for five years, and the final one is completely impossible to get. The first two can be acquired by adjusting your computer's date and time settings, the third seems to be handed out at random, if YouTube evidence is to be believed.
Unwinnable by Insanity: Happens in the original mod when you get off of the elevator between the time when you push the button and when the elevator doors close.