It's hard to believe that it's been more than five decades since The Sound of Music was released. Now, 52 years since its debut, the cast of the classic musical shared exclusive on-set secrets with Closer Weekly, and you won't believe what they're spilling!

Those iconic first scenes of Maria spinning around in a field, looking as effervescent as the Austrian mountains that served as her backdrop, were actually not as magical to film as you may think. According to the film's breakout star, Julie Andrews, the actual logistics of filming her singing lyrics like, "the hills are alive with the sound of music," was fraught with physical complications. "A giant helicopter came at me sideways with a very brave cameraman hanging out [its] side," Julie, 81, revealed. "Every time he went around me, the downdraft from the jets would fling me down into the grass."

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But ever the professional, Julie's tenacity enabled her to get the final shots which still stun crowds today and serve as the movie's truly iconic opening scene. The 1965 musical by Richard Rogers and Oscar Hammerstein II is the third highest-grossing film of all time (after inflation adjustments), a feat Angela Cartwright — who played Briggita von Trapp — maintained is a testament to the movie's charm. "There is just a magic about it," Angela, 65, told Closer.

While Julie welcomed the role of Maria with open arms, fresh off her gig as the lead character in Mary Poppins, the casting directors had a more difficult time convincing Christopher Plummer to take the role of Captain von Trapp. Christopher was a well-trained theater actor and proved to be a more difficult sell. "He didn't think the role was very interesting," Barry Monush, author of The Sound of Music FAQ, told Closer. "He wanted them to build a more intriguing character."

Despite his on-set grumpiness, Christopher, 87, was always vocal about what a wonder it was to co-star alongside Julie. "They got along famously," Barry said of the on-screen couple, who fall in love as World War II looms. They weren't the only two on-set to get along swimmingly. The child actors did as well, despite long hours spent rehearsing.

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"The 'Do-Re-Mi' sequence is not one day's worth of work," Debbie Turner, who played Marta von Trapp, told Closer. "It probably was a week's worth." In fact, lip syncing the lyrics proved to be one of the more difficult tasks the number required. "We recorded all the songs and the whole cast album before we filmed anything," Nicholas Hammond, who played Friedrich, told Closer. "Because 'Do-Re-Mi' was so complicated — we had a lot of extras, horses, bicycles, and dancing — it was particularly difficult for us kids."

"We did our bicycle rehearsal on the back lot of 20th Century Fox, I think on the Cleopatra set," Debbie, 61, said. The choreography would later be filmed on location in Austria. "I used to ride on the back of the bike with Julie Andrews, even though I was probably too big to be on there." One of the things most of the child actors remember from the set was Julie's kindness toward her younger co-stars. "She truly was exactly who you saw in the movie," Debbie shared. "If we were getting rambunctious while they were setting up a shot, she'd pick up a guitar and start singing with us. And she'd have a good, clean joke to tell!"

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Another unforeseen complication the cast had to work with was the Austrian weather. "We had what was on record as the worst spring weather [Salzburg] had in 50 years," Nicholas, 67, remembered. "It rained almost every single day. In an awful lot of the shots where it looks sunny, it wasn't at all. They had to blast a lot of huge arc lights to try to make it look like the sun was shining." But Salzburg's uncooperative weather was little compared to its citizens who were rather outspoken about not wanting the filmmakers there because of the political nature of the movie.

"The town didn't want us there. They provided no cooperation whatsoever," Nicolas said, explaining that the local marionette theater refused to let their puppets be used in "The Lonely Goatherd" scene. "They said, 'This is a classy operation we do here. We don't want them in some tacky Hollywood movie.' So the puppets we used had to be made," Nicholas continued. The children didn't just bond over filming or their shared status as outcasts in Austria. Kym Karath, who played the youngest von Trapp, Gretl, revealed that school time was even fun.

"Going to school with everyone was fun," Kym, 59, told Closer. "Even though I was five and didn't have to go, I wanted to! I tagged along and they gave me stuff to do." The Sound of Music cast is proof that rehearsal doesn't always work out the way it was intended to. Especially when there's swimming involved. "We rehearsed it six times where Julie falls and immediately grabs Kym," Nicholas said of the river scene in which the von Trapps all fall into the water. "But in the actual shot in the movie, Julie loses her footing and goes over the back of the boat, and Kymmie just sank to the bottom of the lake!"

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It was a non-rehearsed mistake that consequently terrified the young actress. "It was 10 seconds before anybody realized there were only six kids in the boat, not seven," Nicholas said. "All those crew guys went rushing into the lake and pulled Kym up and she promptly threw up all over Heather Menzies, [who played Louisa von Trapp]!"

The poor weather affected the filming more than many fans may know. It pushed back filming so much so, that many of the children endured many major growing pains while in Austria. "I was seven and I lost all four of my teeth across the bottom," revealed Debbie. "Then I lost all four across the top so I had a retainer-type-thing that had fake teeth on it!" Nicholas also experienced some major changes evident in the film. At the start of filming, he was 5'3" but soon shot up six inches higher throughout the course of production. "It was a huge growth spurt!" Nicholas, who was 14 at the time, said. "The wardrobe man would joke to my mother and say, 'Why don't you just hit him over the head so he stops growing?'"

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"I started with great big lifts in my shoes, but then they took them out and I eventually had to stand barefoot because I got to be much taller than Charmian Carr," he said, referring to the late actress who played the eldest sister, Liesel von Trapp. Even Kym grew over the production period, so much so that Christopher asked for a lighter child to stand in for her during the final scene. As the Captain carries Gretl into the mountains, that is a stunt-double, not Kym on his back, as Kym grew too heavy for Christopher to carry.

With so much time spent together in close quarters — The Sound of Music took a total of nine months to film — it's no wonder that the cast is still close to this day. "It took nine months to film the movie in its entirety, and we had a lot of interaction, birthday parties, etcetera," Kym said. "We're on email or the telephone all the time. We're not kidding about it being a second family."

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While it is certainly a second family for the child actors who grew up together, it oftentimes feels like a second family to the passionate viewers watching the timeless film. It's a sentiment Nicholas has heard many viewers express over the years. "I've heard people say that when they grew up they used to dream they were one of the von Trapps; that they had parents and siblings like that," Nicholas said. "I've heard touching stories from people who've shared many ways the film helped them get through really challenging times."

And for that kind of longevity and impact, the cast is immensely proud. "We feel very fortunate. All of us feel blessed that we were able to be in something that's given so much pleasure and has had such a positive effect on so many lives," Nicholas added.