Something is wrong with Dolores' memory

Ever since Creepy Bernard started a secret two-person book club with Dolores in an unknown basement themed around the idea of "change," her reveries have turned into something else. In this episode, she finds herself in the night version of her narrative: she sees her dead dad and gets pulled into the barn. That's when things really take a turn. Not only does she miraculously find a gun in the hay, she's able to pull the trigger -- unlike earlier, when Teddy tried to teach her to shoot -- and she manages to send a bullet through the neck of milk-fiend robo-rapist Rebus.

But each of Dolores' real-time actions seems to be informed by a memory of her in a similar situation. So when she finds her father dead, it's first the new version of Peter Abernathy, the guy with the mustache, as well as the old one who'd found the photo and glitched out. And when she aims the gun in the barn, she does so at both Rebus and the Man in Black. When she rushes back outside, her newly bubbling up memories aid her by reminding her she'd been shot in that scenario before and guide her to get out of there. It’s a little like when you’ve finally played a video game enough that you know all the pitfalls as they come, and you adapt your gameplay to beat them. Dolores' memory is her Game Genie.

Which brings us to White Hat William. When she runs into him and passes out in his arms in that final scene, that's almost definitely her memory playing tricks on her from a previous narrative.