There were three parts of the interview process. #1 general call from outsourced HR rep about background and interest in BK- #2 Call with high-level manager with many more behavior interview questions; this lasted about 45 minutes- #3 Invited to BK headquarters in Miami. There were four different people I interviewed with (including the CEO which was cool) and also at times people came into the conference room with me and the 9 other candidates to have conversation. The interviews were different styles, some more conversational and a harder "stress" interview with some math and case questions.
They also talked a lot about their culture to make sure the candidates were a good fit. The culture is casual in the way of dressing and communicating (there are no offices, only desks) but also extremely intense and competitive among employees. There is little outside work life, 12-14 hour workdays, and very high job turnover rate so be sure to know this if you are applying.