Seemed British?

I don't think so maybe some of the dialog like *beep* all but that is about it

Yes! At one point someone says "we'll meet you at ours" which is the British way of saying "meet you at your place" but no one had an accent sooooooo

This is funny because I didn't know much about the film before seeing it and I remember assuming it was British even before anyone spoke, just by the cinematography alone.

As it was obviously set in America and everybody was American, I would say no. You're insane.

I thought it was pretty clear that it was filmed in and set in the US. However, the line that you quoted definitely caught my attention. Also in the film, a character says, "We'll meet back at ours." Another very British thing to say. After those two lines, I was purposefully listening for other examples but didn't hear any.