US grammar quirks from a Brit's perspective

UK: drag, dragged
US: drag, dragged... or out in the sticks, drug
Comment: Drug as the preterite of drag is country language, like saying "stood in bed" instead of "stayed in bed."

UK: dive, dived
US: dive, dove (egads!)
Comment: I think dived is also used in US English, but maybe not as much as dove.

UK: Get that Englishman off my screen!
US: Get that Englishman off of my screen! 

Comment: I would teach the adding of of as incorrect, but that's changing.

UK: Where are the burglars?
US: Where are the burglars at? (I'd agree that's redundant, but it's common informal US English, with variations depending on education and ethnicity.)
Comment: The addition of at is colloquial, as in "Where you at?"

UK: I'll see you on Friday.
US: I'll see you Friday. (I don't think I'd even notice a difference.)
Comment: In the US, people also say "on Friday," but it's true that we often leave out the on. This also happens with "I'll write him tomorrow" as opposed to "I'll write to him tomorrow."

UK: I've already eaten.
US: I've already ate.
Comment: I'd definitely teach "I've already ate" as the utterance of an illiterate moron. I'm sorry the guy had to encounter such barbarity, but you never know what those damn uneducated Yanks are going to say.

UK: We're open from Monday to Friday.
US: We're open from Monday through Friday. (But we also use to.)
Comment: Here, I'll defend the American choice. Logically, saying "to" can be interpreted as "up to and not including," so "Monday to Friday" could potentially mean "Monday, up to midnight at the beginning of Friday." The preposition through eliminates this confusion: by saying "Monday through Friday," we now know the place is open all (business) day Monday until the very close of business on Friday. There should be no cause for confusion here.

UK: This guy's channel is really good.
US: This guy's channel is real good.
Comment: Again, this is informal, often hickish language. But yes, there are cases of "real good" to be found outside of the sticks.

UK: I'm doing well.
US: I'm doing good.
Comment: Informal US English for sure. Guilty as charged. You good with that?

Both of the above examples point to a quirk in US English: the improper-but-frequent use of adjectives in place of adverbs. Think of the Apple advertising slogan from a few years back: Think different. Or the people who bid you, when you leave, to "Drive safe" instead of safely. It's incorrect and occasionally annoying, but it's part of the fabric of informal US English.

Meanwhile, the Brits have une fâcheuse tendance de start(ing) sentences with Too instead of using the more proper Also (more proper to Americans, at least). That's all I'll say for now. Given how many UK personalities I watch on YouTube (especially about cooking), I have a whole, long list of Britishisms that annoy the hell out of me. But I'll save them for later.

UK: X is different to (or even from) Y.
US: X is different from Y. (or) X is different than Y.
Comment: There is a rule for this. In the UK, it's generally different to (how often do the Brits say "different from"?). In the US, it's generally different from. But when there's a clause, in both US and UK English, you have to use the comparative than. "The results were different than I expected." The words "I expected" form a clause.