Zach Mills in Mr. Magorium's Wonder Emporium Courtesy of Fox Walden

If something is thrown into the air and disappears, a crew member probably caught it off camera; if something moves, there's likely someone hidden behind it, pushing it around.

"Kids are far more sophisticated than they've ever been," Helm continues. "They have a much deeper and more complicated understanding [of films and stories]. You have to challenge them. The natural way to challenge them is to make things quicker, louder, bigger. This film isn't exactly the antithesis to that, but we're asking kids to look at the movie more with a sense of imagination and play. We have numerous scenes with nothing said. We spend time in the internal world of these characters. It's exciting to try that with a younger audience."

Regardless of age, everyone was pretty gaga the day Kermit the Frog showed up. "The man who manipulates him is 6 feet tall, beard, long hair," Helm says. "He's standing right there, he's got all this equipment on, but you can't help but talk to Kermit. It's as if the man is invisible. And any day that Zach Mills was on set was always great. He was so excited to be there, he reminded us who we were making the movie for."

Mills certainly reminded Helm of something: they not only share a first name, but Mills could be Helms's younger brother — his younger self. "It was down to Zach and another boy, who, funnily enough, looked like my [producing] partner, Jim, who's a surfer," Helm says. "This other kid walked in with jam shorts and a Billabong T-shirt, floppy hair, he was so loose. Zach wore a button-down shirt, jeans, and tennis shoes." Helm gestures to his own, identical outfit, then to his ears, which stick out slightly. "And Zach has the ears. And the way he'd say [here Helm does an impression of himself], 'Oh! Hi!' I said, 'Jim, we're trying to cast ourselves. But I win.'"

Still, when CGI was necessary, it was comforting to have Portman around, Helm admits in the garden of the Hollywood post-production facility where he's editing Magorium's five months later: "Out of everybody on the set, she was the most experienced at shooting effects. She'd just done three films [the Star Wars prequel trilogy] where she had to imagine other actors based on dots on a wall. So she was a pro, nothing phased her."