EDIT: Looks like the above is a matter of preference in American English rather than a strict grammar rule.
There are a few differences like that which can appear jarring at a glance. Another is punctuation inside quotation marks, where Americans always include trailing punctuation inside the quotes but elsewhere it's only included if it's part of the quote. The subject of dashes, whether - or -- or — should be used and whether or not they need to be padded with spaces, seems to be a particularly gnarly one and seems to be more the preserve of style guides than anything. And then there's the Oxford Comma, something that is totally not at all controversial.
The capital-after-a-colon is new to me though, optional or otherwise.
