Kevin Costner's son Hayes reveals what it was really like to work with famous dad in rare revelation

Throughout promoting his passion project Horizon: An American Saga, Kevin Costner has been a proud dad gushing about his son Hayes' brief role in it.

The former Yellowstone actor — he confirmed his exit from the show just last week — has admitted he "selfishly" cast him in the project to spend more time with him, and further shared during a recent appearance on the Today Show: "He's a beautiful boy and he's quiet," adding that Hayes, 15, accomplished a "really beautiful" performance in what he described as "a really complicated scene."

Now, ahead of the official release of the highly-anticipated first installation of the four-part Western saga, Hayes himself has given insight into what it was really like working with his Oscar-winning dad.

Speaking with Entertainment Tonight at the Los Angeles premiere of Horizon, Hayes equally gushed about working with his dad.

"I just thought it was really cool, it was an amazing experience," he said of seeing the film — and his role — come to life on the big screen.

He endearingly added: "I was just really proud of my dad, he's been working for so long, and I just could only think about him at that moment."

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Kevin certainly left an impression on his son as his director and co-star, and the teenager confirmed he'd love to keep working with him. "Yeah I love it," he said. "It was super fun. He taught me and he was there alongside [me] all the time."

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"It was awesome, I mean I got to spend the whole day with him everyday and just see him work, and I just had such a blast, it was amazing," he added of spending some weeks on set with his dad.

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Much as he loved it though, now he's ready for the two to spend quality time away from a movie set as well, and shared: "He's so busy [but] I really hope so," about getting some family vacation time, and revealed: "I think we're going to the Bahamas soon and I'm glad."

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Hayes is one of the three kids Kevin shares with his ex-wife Christine Baumgartner, who he was married to from 2004 until last year, and with whom he also shares Cayden, 17, and Grace, 14. He is also a dad to Annie, 40, Lily, 37, and Joe, 36, who he shares with Cindy Silva, his wife from 1978 to 1994, and Liam, 26, with former partner Bridget Rooney.

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Though the first part of Horizon only just premiered in Cannes this year, Kevin has been working on it for so long that in fact Hayes was named after a character his dad wrote for the project before he was born in 2009. 

Also speaking with Entertainment Tonight in April, Kevin joked: "I was watching him grow up and I was thinking, 'Man I better get with it and make this movie.'" He added: "He's very good in the small part that he's done," and emphasized that in spite of the brevity of the role, he nonetheless has a real "impact" on the movie.