Past "memories" have shown Dolores standing around dead bodies; presumably this is a vision of the oft-alluded-to incident that occurred in the park 30 years prior to the present-day events of the series, and the third episode's final beats, in which Dolores pictures the Man in Black, shoots a bandit host, suffers a shot to the abdomen herself, and then flees back to William, all seemingly in the same stretch of time. If Dolores is connected to The Incident -- and come on, she has to be -- it's likely she went through the maze years before hearing about it from Bernard in "Dissonance Theory."
The Las Mudas moment bundles all the evidence together. William seems to have led her there in the past, intentionally or not, and that experience is what's drawing the older William (the Man in Black) back to decipher the maze game. It can't be just a coincidence that the Man in Black stopped in Las Mudas before continuing on in the game. And if what I'm detecting is true, present-day Dolores is hot on his heels, her memories giving her an advantage.
"Dissonance Theory" makes a point of juxtaposing William and the Man in Black; not only do they not share any scenes together, each of their moments are dropped into place like diptychs. Dolores will talk to William about herds of cows brought back to the slaughter and then the Man in Black appears cliffside, ready to ride into a shootout. Westworld is meticulous on every level, framing things just so in order to play by hidden rules and convey the sensation of an awakening mind. Not only is Dolores' perception coming into focus, it's beaming through constant repetition -- a mundane enslavement. Nolan and Joy's formal choices amplify the confusion and terror -- Dolores' and our own.
Is this legit? Westworld is too skilled at being enigmatic to know for certain. But Dolores' mind, rich with reveries, is spinning and jolting out of control. As Ford said earlier this season, "It's a tricky thing weaving the old into the new."