Okay, I have to confess I see no reason why you shouldn't have American cultural references when you are writing stories based on characters supposedly living in America, or where the majority of the characters are supposedly American. What is wrong with that? If the characters/setting is the UK or NZ or France or where ever then it is perfectly reasonable to assume there will be terms, products, etc that are not common in the US. I have lived, traveled and read enough to expect this. Frankly, I think it odd that there are those who are upset by it.

I have no problems with the spelling being British versus American; it's just a quirk of the language shift. There are some words that I spell one way and some I spell the other - causing my spellchecker to have a nervous breakdown. ;-)