While speaking to ET via Zoom, the two marveled over the impact their dad has made in Hollywood, starring in movies like Top Gun, The Doors, Heat and more. The 61-year-old actor spent decades finding his voice through characters, but underwent a tracheotomy years ago and now speaks through his tracheostomy tube.
"What I'm very proud of about our dad is that he trained at Juilliard. He's a very dedicated intellectual actor, classically trained actor, but he also has a very populous mentality," Mercedes told ET's Denny Directo. "He's always really had a lot of reverence for big Hollywood pictures. I think he's been able to do something that not many people have, which is to bring that level of craft into these big, comic book acting, like big Hollywood movies, because he's always really loved the entertainment for the people."
"I think he could have had a more academic elitist career, but that's something that I think is his legacy," she continued. "That he has been able to integrate a lot of what is great about American film, entertainment and theater."
Jack echoed Mercedes' sentiments, and compared his dad to three other high-profile celebrities: "He's a combination of Marlon Brando, Britney Spears and throw in Jimmy Hendrix too."
Jack and Mercedes also opened up about their father's all-new documentary, simply titled Val, in which he takes a look back at his life in the public eye. They're both featured in the documentary through intimate home movies and behind-the-scenes footage from Kilmer's impressive decades-long career in Hollywood.
"My dad started making this movie in the '60s. He's always documented his life and he's been very ahead of the times in that respect," Mercedes shared. "Him and his brothers would make little movies and just document everything when he was younger, but with a real cinematic eye as well. It's been a long time coming."
"The entire movie made me emotional," she continued. "It did really surprise me to see it with an audience. I'm so used to people not understanding my dad, and his public image being different than the playful, funny person that we know. It did really move me and surprise me to see audiences really see him for the first time. That was incredible."
Jack narrates his dad's writings, and told ET that he thinks his father wanted fans to see "different sides of him."
"I think he really had something to say about life, and about creativity," he explained. "I'm not quite sure how to articulate that message but it's very clear in the film that he loves life and he is dedicated to creating and being a creative person."
"My dad is really dedicated to acting and he doesn't really talk about his process that often," he added. "Maybe that's because he's at a ninja level of acting. But just to see him as a young man and learn this craft is just so cool."
Val is available now on Amazon Prime Video. Hear more in the video below.