Our Betters

Elsa Maxwell was brought in as technical advisor for this film because of her vast experience in hosting events for royalty and high society. She also assisted Hattie Carnegie in the designs for the evening gowns worn by the principle actresses.

Although Bessie is supposed to be from New York, Anita Louise plays her with an affected British accent.

A person's accent is not "cast in concrete". Accents change due to a change in environment or because a person is trying to blend in (or even acting). Regardless, a questionable accent certainly wouldn't be considered a "Plot hole".