It's been fairly apparent this year that via their ear pieces, officials on the field are receiving input from someone off the field. It's happened on multiple potential "game changing" calls that were not under review or challenged (e.g. kick catch interference in the Steelers game last night). The normal routine is the officials huddle to "discuss" it, but it's obvious they're waiting on input that's communicated to them from somewhere.
Side note, I'm 100% fine with this, but feel the league should be more transparent about it.