Fans of “Stranger Things” have made a theory that there is a bonus episode waiting to air on Netflix. That has led social media accounts to put "ALL EPISODES OF STRANGER THINGS ARE NOW PLAYING" in their bios. So, no, there is no bonus.
Show star Noah Schnapp has also made it plain that no bonus episode exists by saying that the Duffer brothers “really left nothing more to be told." The mystery episode rumor said the episode would air today…so don’t be disappointed that it's not on the streamer.