I'm sorry, and while that sucks, I would be cautious to cancel the flight. My gut feeling is that them not hiring you has little to do with this trip and is based more on concerns about your availability with your school schedule coming up next year. You said that many people were interviewing for this position, right? Unfortunately, I sometimes conduct interviews where I work, so I know what employers are looking for. Especially right now with the economy, companies want to hire few people that are the best suited for the company, esp as far as availability goes. If we have a group of applicants including one college student with decent availability for the summer that will soon change to limited availability for the school year vs someone who is not in school with open availability year-round, you can guess who we're going to pick. Just my two cents there. Sorry you're disappointed, but keep looking around - you'll find something else.

Put in applications everywhere, and be persistent.