FLASHBACK: Mary-Kate and Ashley Olsen on Pressures of the Spotlight on Their Last Film Together (Exclusive)

ET was on set of 'New York Minute' with the 17-year-old Olsen twins in 2003.

Fifteen years ago today, New York Minute hit theaters -- and it marked the end of an era. 

The 2004 comedy, which starred Mary-Kate and Ashley Olsen as polar opposite twins, Roxy and Jane, who are brought together through a crazy day in the Big Apple, was their last film together after dozens of credits. There were no signs of the then-17-year-old actresses' plans to take a step away from Hollywood when ET caught up with them on the New York Minute set in 2003. In fact, they gushed about their plans to expand their roles in entertainment. 

"Directing!" Ashley lit up when asked what she wanted to do next after the pair graduated from college. They were about to start their senior year of high school. 

"Obviously not right now," Mary-Kate excitedly added. "I'm too short still. Too little. You feel young." 

Mary-Kate and Ashley, who would go on to attend New York University, weren't worried about how their classmates would receive them. "[It's] what we have to do in our everyday life," Mary-Kate reasoned. Ashley, meanwhile, had gotten used to difficulties "keeping everything private and personal." 

Mary-Kate and Ashley Olsen film 'New York Minute' in Manhattan in October 2003. - James Devaney/WireImage

The pair, who were also producers on New York Minute, wanted to go "bigger" for the movie. The film had them breaking heels, crowd surfing and running around Times Square in towels. "That was a little nerve-racking," Ashley confessed of the towel scene during the movie's press day. "It was an interesting experience I'll always remember."

Through it all, however, she had her sister. "[We're] so important to each other. I mean, we're kind of just connected," Ashley said with a laugh. 

"We always know what we want, but if we're stuck in a situation where we need justification or something like that, we turn to each other," Mary-Kate added. 

They worked together on the cast, which included Eugene Levy, Dr. Drew, Andy Richter and a cameo by the twins' Full House dad, Bob Saget. "For the whole casting process, we made a wish list and went after the people that we really wanted. We got most of them and we were very pleased. We actually did make a couple personal phone calls." 

Mary-Kate and Ashley Olsen pose with Bob Saget while filming 'New York Minute' in October 2003. - James Devaney/WireImage

As for their love interests in the movie, Riley Smith played Ashley's, while Mary-Kate's was none other than Supernatural star Jared Padalecki. 

"The only hard part was he was so tall, I had to stand on apple boxes [to kiss him]," Mary-Kate confessed of starring opposite Padalecki. "But that's how it usually is. All the other movies, we always pick the really tall guys for some reason."

Ashley had a boyfriend while filming New York Minute, but told ET that enjoying true alone time with any significant other wasn't easy. "You can try [to fly under the radar]. Not really though. Not right now at this point," she said. 

"Sometimes [paparazzi] jump out of bushes, follow you home but you just have to know it's part of the territory," she continued. "It's not a sudden thing." 

"It's not a sudden thing, but as we get older, driving or whatever, it becomes really dangerous," Mary-Kate chimed in. "But everyone wants a good story." 

Riley Smith and Ashley Olsen film 'New York Minute' in October 2003. - Mark Mainz/Getty Images

Though they were at the height of their fame -- Mary-Kate and Ashley had built a fashion line of their sisterhood, had a TV show, done multiple movies and were about to skip their senior prom to host Saturday Night Live -- their desire to pull away from the spotlight was evident. 

"[For our 18th birthday, we'll do] just a dinner probably," Mary-Kate said. 

"I think more than anything, it's the timing of our birthday, graduating, going off to school and the movie coming out," Ashley said. "It's just all kind of happening at the same time." 

While Mary-Kate went on to act in a few more projects, both she and Ashley have transitioned their focus to their fashion empire. See more on Mary-Kate and Ashley in the video below.