As any Australian or other “English”-speaker knows, English is being ousted in “favor” of American at a depressing rate and too few are worried about it. English sets us apart from the rest of the riff raff and is a symbol of our education and heritage at once. The following should, by no means, be new to anyone but it’s here in the case of it being so.

Vocabulary

Rules

Punctuation

Quotations
In American, terminatory punctuation rules are disregarded when quotes end the sentence. This leads to ambiguity of the writer’s intention. Take the following American sentence as an example:
He said “You will?”
The American reasoning is (of course) to shorten the process for “efficiency” but in this scenario, we’re left wondering who’s actually asking the question. The narrator or the person being quoted? Americans claim that it is the narrator, not the person being quoted that owns the question mark! This is impossible though - quotation marks encapsulate the quote and punctuation falling within them clearly must belong to the quote. To English eyes, this leaves sentences looking bare and without end as they lead into the next with an odd capital letter in the following word. An example in English would be:
He asked if you’d “Had fun already?”?
Any combination of full stops or question marks would leave the sentence valid but convey different meaning which is impossible with American punctuation. For further clarification, in the English example, both the speaker and the quote are questions - impossible to convey with American standards.