The Doctor suddenly appears in the Oval Office, while the rest of the team stays on the cloaked TARDIS, and there's all kinds of American chaos, and River keeps saying she hates the Doctor so he can smile and say she doesn't hate him, and they discuss how "Jefferson" is, in fact, a little girl, and the Doctor sasses everybody without actually saying anything for approximately ten minutes. Canton proves his worth by pointing out obvious things that get us over the narrative obstacles -- "Mr. President, that man walked in here with a big blue box and three of his friends, and that's the man he walked past. One of them's worth listening to" -- so... Now we like Canton!
It's really that easy, when your viewers have huge parts of their identity wrapped up in loving a forty-year-old franchise regardless of the quality on any given day. When loving Doctor Who is more important than actually watching Doctor Who, it's just that easy: Make sure somebody shit-talks authority while clearing the Doctor's path, and you know he'll end up a hero. Or at least onscreen, for a long time, without ever developing a personality of any kind.
Nixon tells everybody to shut up some more, and the Doctor makes himself at home in the President's chair, yelling about fezzes and jammy dodgers, and a short time later we've decided to go to Florida. ("She mentioned a spaceman, NASA's where the spacemen live.") Amy and River have a little conversation about five minutes ago when that spaceman shot the Doctor, in case you missed that part, and then Amy spots a Silent in the corridor outside the Oval Office. Rory distracts her, and she forgets about it immediately. Something happens with her womb/perception of spacetime -- same thing when you're a woman, am I right? -- and she runs off to the bathrooms (but only after Canton yells at a Secret Serve guy, of course).
In the bathroom -- "Actually, I can usually manage this alone," she tells the Secret Serviceman, which is pretty cute -- Amy recognizes the Silent in there (Same one? Different one?) as being similar to the skinny shape she saw at the lake and then forgot. A lady comes out of the john and squeals at the thing, then forgets it's there, and then squeals at the thing, then forgets it's there, and so on, until finally it just sucks out her brain juices magically, and then she is dead. Amy takes a camera phone picture of the thing, which you'd think would matter but of course never actually matters.