Probably one of the easiest processes I've ever been through. Keep in mind this job is really friendly for people as their first job. This was my first job interview & job, and the process was a breeze. I went to customer service before watching a movie, asked for an application, filled it out & turned it in on the spot. It was a basic piece of paper - it just asked for your job history (some people don't put anything and still get the job, I put all my volunteer & leadership work I did during high school) & basic info.
About two or three weeks later I got a call asking for an interview. Day of, I dressed up in slacks & a button up with a tie. I went to the theater's customer service & they gave me a paper with instructions of where to go. The actual offices were on the second floor, which was accessed by an elevator hidden behind concessions. I was a little early, and there was a person waiting to interview before me. He was wearing jeans and a t-shirt. I got called in & it was an individual interview in an office with one person on the other side of the desk asking me questions. Sat down, and was asked some pretty basic questions. Things such as "why do you want to work for us", "tell us about a difficult situation you've had", "tell us about a conflict you've had with a superior and how you handled it." It was just stock interview questions.
After the interview, I got a call back saying I was hired and when & where to be for orientation. After working with the company for two years during high school, I can say it's one of the easiest hiring processes around. The hiring manager told me that they interviewed everyone who submitted an application. They've hired people who have shown up in casual clothing, although it's best to go business casual (do not overdress for the position. A suit is too formal, but it won't matter much anyway). The absolute best time to apply is before summer or before the holidays. Think maybe April or May for summer or September or October for the holidays. This is when they actually hire. The company never hired outside of those two periods because they did not have the hours for it. Your theater may differ, but typically the busiest times of year are summer & winter. My theater also did not do seasonal hires, so you would keep your job until you quit or were fired even after the busy season. A lot of people would take leaves of absences and only work as seasonal employees, but that was a choice. It's not like retail where they hire you on for 90 days or whatever. Once you're in, you're in (just expect your hours to drop after the busy seasons). Don't overthink it. It's simple. If you have any job experience whatsoever you're probably a shoo-in. If not, just talk about ANYTHING in the past that has shown that you may be a good worker. Most of the people they hire are in high school or just out of high school. It's a great way to start building job experience.