One thing I usually forget when I go on vacation to western New York is that I’m in “pop” country; “soda” means club soda. If it comes up, I make the mistake once, and then I remember … until the next trip. I grew up on the other side of the state, in “soft drink = soda” country. However, I don’t recall it being so much an issue in some other map areas — they’ve got Orlando, Fl as a “Coke” area, and The Willamette valley in Oregon looks like it’s supposed to be a “pop” area. (Orlando has so many resettled folks, though, that there are lots of ways that it doesn’t seem like the south. Get outside of town, though, and that can change in a hurry)
The largest linguistic difference I recall from CorVegas was “sack” instead of “bag” at the grocery store.