The FA demanded an explanation for the bottle thrown towards referee Uriah Rennie at Loftus Road on Tuesday night.
The missile was hurled from the home section of Loftus Road during the 2-1 home defeat by Sunderland on Tuesday - and boss John Gregory condemned the action.
A statement on the FA website read: "The FA has written to QPR and Stoke City requesting information with regard to missiles thrown from the crowd during the matches against Sunderland and Cardiff City respectively on Tuesday 28 November."
Rangers boss John Gregory added: "We can do without this sort of thing and I think we could get punished for this. The authorities need to clamp down on it.
"Blaming the officials is pretty lame, because Sunderland deserved all three points."