Two short lists

Some of the ideas I had are not true.

People don't seem any louder and more assertive than back home. Perhaps it's just a survival method employed by Americans overseas. Or perhaps I am already used to it and am doing the same.
Not everyone is overweight. Although a few are.

Some of the ideas I had are true.

I don't think I've ever walked - or otherwise moved around under my own power - so little in my adult life as during this last week. The car is the star.
Everything is bigger here, but perhaps not quite as big as I had expected. I guess people will tend to talk in hyperbole when describing visits to faraway places, as a form to amplification to counteract the attenuation of distance and time. But you'll need to remember to cancel it out when visiting these places for yourself.
There sure are a lot of American flags around. I generally don't like flag-flying (or any display of nationalistic pride), although from an aesthetic point of view there is something quite beautiful about them, especially since the seem to fit so well with the landscape, as indispensable to the scene as the road signs, fast food joints, liquor stores and pick-up trucks. It's no accident that so many countries have chosen flags of red, white, and blue; my own has only the last two, which means our flag tends to get lost against the sky. The American sky is big, but the stars and stripes can deal with it.
I have been struck in some other parts of the world by the feeling that everything is new, as if history is in general an inconvenience. In Detroit, there's very little that isn't old: cars, buildings, roads, furniture, and a good deal of people seem to have been slowly aged, like cheese or whisky, so that all the new paint and sharp edges are gone. It gives the place a soft feeling, something very analogue, a cracked old recording which resists all forms of digitisation. And no-one moves around very fast in these parts.