The actual restaurant used during filming was Carrow's Restaurant in South Pasadena, CA.
The use of the burger-holding figure at the front of the restaurant is an obvious homage to the various "Big Boy" franchises around the US.
Sarah Connor is frequently referred to as a "meek waitress" or "lowly waitress". But, according to the script, the day she is shown waiting tables in the original film was actually her first and only day as a waitress. She had previously been a busser/dishwasher. Nancy was her trainer that day.