"We'd read a bit each night and I saw where they giggled and laughed and said, 'Go back. Read that part again,'" McConaughey recalls. "That's something I find fun with all the scripts that I do. I don't read them all to them. There'd be a lot of beeps."
The 3-D stop-motion animated adventure follows a young boy named Kubo (voiced by Art Parkinson), who must locate a magical suit of armor that once belonged to his late father in order to defeat a vengeful spirit.
Co-star Charlize Theron says she's looking forward to making fans out of her two small children, Jackson and August.
"It was really nice to find something that my children could actually see," Theron tells ET. "They would have to be at least 52 to see any of my work."
That other work includes the upcoming Fast 8, which she teased in our interview.
"I don't drive in Fast 8, not to bust anybody's bubble," she reveals. "There's a surprise element. I'm not doing what those guys are doing so well already. I'm coming in and doing something a little different."