The American's don't have the peculiar paranoia about people stealing coat-hangers from hotels that you find in Europe - everywhere we've been has had real hangers, none of those weird nubbin headed hook-in hangers that feature in almost every hotel I've been to back home.
Toilets are not as universally similar as you might think (or at least as I thought) - around half the toilets we've encountered here have the bite mark out of the front that I've only ever seen in schools in the UK. They also have a completely different flushing system, which is weird as you would have thought there would be one best way which everyone would use, but then what do I know about plumbing?!
TV advertising is completely different here too - there's the usual lack of restriction on naming competitors and comparing features directly, but there are also a surprisingly high number of ads for prescription medications, and a worrying tendency to have disclaimers at the bottom of the screen to tell people that the stunts are performed by professionals.
Driving seems to be a much less disciplined affair - it may just be in Manhattan that there is such a love of horn honking, but while we were there there was constant blasting at traffic lights including a particular honk which seemed to mean 'I reckon the lights are about to change, and I'm not sure you're as ready to move off as I would like you to be'. Coming from the UK where you can easily go for weeks without hearing a car horn, it was particularly perturbing to hear them every two minutes and used by people travelling in free-flowing traffic, apparently just to hear themselves making a noise.
Eating out is quite an adventure - with the exception of maybe two places, we have been given a glass of water as soon as we've sat down everywhere we have been. When we've ordered soft drinks, they mostly seem to come with a shed-load of ice and a straw with a tiny little paper hat on the drinking end, presumably to demonstrate that the straw is clean, which I would have believed anyway. Aside from the three egg minimum, there also seems to be a love of 'home-fried' potatoes, which come in plentiful supply with almost every breakfast order and consist of pretty much anything you can fry up with potatoes.
There were a few food items which we were previously aware of being named oddly, like eggplant, zuchini and capsicum, but we have also come across cilantro (coriander), arugula (rocket), rutabaga (swede) and the peculiar incomprehension of the concept of squash (in terms of a drink cordial).
One of the main things which impacts on us is what we call 'random taxation' - tax is applied to the advertised price, but apparently according to some potentially unfathomable system which we have yet to figure out. Sometimes we are taxed at around 10%, sometimes more and sometimes less and although we know that anything pertaining to tax is strictly regulated and is clearly not as ad hoc as it seems, coming from a country where tax is always included in the price you see on the label it does seem particularly confusing.
Alcohol - there seem to be two types of shop, those that sell wine and spirits and those that sell beer. Why the two haven't met, I don't know, but there's no sense to it.
Lightswitches - they are ALL upside down. Everywhere we've been has switches where you hit the top to make the light go on and the bottom to switch them off, which is counterintuitive, a little confusing, and exactly the kind of thing that we will get used to while we're here and then find even more confusing when we get home.