Those maps are both fascinating and amusing. I've run across them before. On the carmel/caramel thing, I thought for the longest time that they were two different words denoting slightly different forms of sugary stuff! I tend to say caramel with all three syllables (like, I'll take two of those gray sea salt caramels, please. How much?? Two bucks apiece? Yikes!), but when browning onions, I'm carmelizing them. Weird. I never thought about it.

I'm sure you're right about the spread of "sub" via the Subway chain. My dad was from Philadelphia, so I grew up with the term "hoagie" even here in Portland. I'm not actually familiar with "grinder".

With the Teen Wolf fandom growing so huge on both sides of the Atlantic, I catch inadvertent Briticisms in a lot of fics, even where the writer is very conversant with American. Dead giveaways, to me, are "straight away" for "right away" and "a coffee" for "coffee." Little things.

On the round breakfasty things: pancakes, hotcakes, griddle cakes, flapjacks are the four names I know for them. And for frying pan, the only other term I can even imagine might be griddle, but in my kitchen, a griddle and frying pan are two very different things.