A couple of things I’ve noticed:
British:
She’s round at a friend’s house.
American:
She’s over at a friend’s house.
B:
They must do.
A:
They probably do.
The usage of the word “jumper” in a novel confused me to no end until I learned it meant “sweater.”
Are you kidding me? Please don’t tell non-Americans that, they’re likely to believe it.
a few of my favorites:
American/British
sweater=jumper
pacifier=dummy
trash/garbage can=dust/rubbish bin
cigarette=fag
bathroom=toilet (Americans restrict the term “toilet” to the device itself, and do not use it for the room in general)
Well I don’t believe it Space Vampire. He’s called Robin all the way through the story, so it’s obviously his name.
There seems to be some confusion about bumpers. On a British car they are the horizontal protectors near street level at the front and back of the vehicle. kferr has indicated that in the US “fender” equates to the British “wing”, not bumper. Is that correct? I believe fender used to refer to a protective metal surround laid on the floor in front of an open fire in Britain.
Careful speakers don’t use those terms interchangeably, but not everybody is a careful speaker. You will hear people saying Britain when they mean UK and vice versa, but it’s just a sloppy innacuracy rather than something politically significant – if you’re talking about British/Irish politics, anyone who doesn’t like “the UK” won’t feel any better about “Britain”.
Maybe you do, but the UK media (including the Times and the Financial Times) are using it to mean a thousand million. So there. 
Everything’s bigger in Birmingham.
jr8, damn! I know, its silly.
Everton, yup, including our traffic jams 
I don’t think that really counts. Everyone knows that it is called the television and a lot of people call it that. “Telly” is a bit of informal slang.
Oh, do Brits say “TV games?”
Not really. Videogames? Computer/PC games is sometime sheard to refer to videogames, but this usage (IMHO) is dyign out somewhat so you have have a more strict videogames on consoles, computer games on PCs.
you push it with your legs.
I think that’s where the term comes from.
Besides, the first bicycles used to be push-bikes. Literally.
You had the frame, the seat, but no pedals. You were supposed to run your feet along the ground as you were sitting on the seat.
here’s a link with pics:
http://www.pedalinghistory.com/PHhistory.html
it was called a walking machine
so there you go.
push bike/pedal bike.
All the same to me
I will wait for a Brit to confirm, but I will tenatively put “TV games” on the list of Hong Kong English to be discouraged.
I am a Brit.
Oh. You and your pesky location.
How about “subway,” does this mean a tunnel for pedestrian traffic to you?
Yes. We understand what it might mean to other people but don’t use that meaning ourselves. At least I think so. Actually, what do they call the undergrounds in Newcastle and Glasgow?
Anyone know?
Sometimes. It very much depends on context and location. Round here, they tend to be called “underpasses”, but I have been to towns where they are known (and signposted) as “subways”.
If I heard and American use the term, though, I would probably assume he was talking about an underground railway.
In Newcastle we call the underground railway “The Metro”
Fancy dress party
In the US, this will usually indicate formal attire: tuxedo/dinner jackets or gowns (as appropriate to one’s gender).
In the UK, this is a costume party.
It is important to make sure you know which type you’re going to. I suppose that if you turn up to the UK version in a tuxedo, you could fake it by doing James Bond imitations all evening. In the reverse situation, however, you might have some difficulty explaining why you wore a bunny costume to a formal affair.
I wonder what they call soft-soled general sports shoes in Hong Kong? The standard term in the UK is trainers (abbrev. for training shoes) but I believe sneakers is slipping in here too.
Nobody seems to have mentioned these yet either:
British/American:
anorak/parka – anorak is also UK slang for a nerd
badger (or mither, pron. m-eye-there)/hassle, verb
biscuit/cookie
spanner/wrench
tap/faucet or spigot?
Swiss roll/jelly roll
off licence/liquor store
paraffin/kerosene
side/English (in billiards, pool etc.)
BTW, chippy is also a slang term for a carpenter in the UK. Fag is slang for cigarette, but ciggie and tab are just as common.
I believe the Subway is a nickname for the underground railway in Glasgow, as is the Clockwork Orange.
This site lists lots more examples.
Here’s one from the Getaway (the PS2 game). Whenever you bump another car the person yells out “Come back, I need your details!” If that happened over here I’d ask, “Details about what?”