Disney's "Frozen" has been a phenomenon. It's been in the top 10 at the box office for 16 straight weeks, bringing in over $1 billion worldwide. It won two Academy Awards, including Best Animated Feature. And it has been analyzed and picked apart by its fans. We've already looked at some of the "easter eggs" hidden in the film — including a Mickey Mouse doll and a cameo from Rapunzel — but there's one more subtle reference few have ever noticed. In fact, even the person it's based on wasn't told about it.

[Related: Play 'Frozen' Find-It With Our Exclusive Guide to Film's Easter Eggs]

The song "Love Is an Open Door," which you can see in its entirety above exclusively here on Yahoo Movies, contains a brief moment where Prince Hans, belting out a high note under a waterfall, closes his eyes and raises his arm in an exact copy of a signature move by '70s singing sensation Donny Osmond. And it was put there by a Disney animator who just happens to be Osmond's nephew.

View photos

Hyrum Osmond is a Disney veteran who has been animating features at the studio since 2008's "Bolt." On "Frozen," he was the supervising animator for Olaf, the lovable snowman, but he stepped in to animate Prince Hans for that one particular moment. In a phone conversation with Yahoo Movies, Osmond said, "I requested that shot, just because I knew that that was the perfect moment to kind of pepper in that Donny Osmond feel to it." After all, the song between Hans and Princess Anna is the kind of bubblegum pop number that made the Osmonds famous.

Hyrum's father is George Virl Osmond Jr., the eldest of Donny's seven brothers, who was born with a hearing impairment and did not perform on stage with his siblings. But he did work behind the scenes, and Hyrum said he spent time watching his uncle and aunt Marie working on their variety show.

"Obviously we were exposed to the 'Donny and Marie' show. We were on set a lot," Hyrum said. "And me and my brothers and sisters almost playfully mocked our uncles with their signature move, which was basically sort of a tilted head, eyes squinting, with the raising of their arm or arms as they belt out that note." So when it was time for Hans to hit his high note, the younger Osmond wanted to pay tribute to that move: "I just thought it was a perfect moment to kind of hit the Donny Osmond pose there."

View photos