As a British English speaker, I was reading a manuscript written by an American English speaker and came across a sentence in the form:
"She had long hair and so had to sit in the back [of the animal that the group were riding]"
As a British English speaker, I'd never use the phrase "sit in" to describe anything other than a person inside a vehicle or object. So I ended up with the comical image of a young lady sitting inside a riding animal, complete with doors and wheels.
I suggested that the sentence should have been:
"She had long hair and so had to sit at the back [of the group/of the animal that the group were riding]."
On reading this, my friend commented that she'd never use the phrase
"at the back" and that the construction didn't even feel grammatical to her. I was very surprised to hear that, since the phrase
"sat at the back [of a lecture theatre perhaps]" is an utterly standard phrasing in my idiolect.
We were wondering if this is a common difference between American English and British English, since our responses were so different.