Zoë Kravitz and Channing Tatum just impressed Simon Rex on the set of Flash twicewith their work ethic.

In conversation with PEOPLE The 50-year-old actor told The 40 Years of the Year magazine at the film’s premiere in Los Angeles how “interesting” it was to watch the “dynamic” between Kravitz and Tatum, as the 35-year-old made her directorial debut with Tatum in the lead role.

“They were so cute together,” Rex said, adding, “It was interesting to watch that dynamic because it’s like watching her say, ‘Hey baby, try this, eh?’ And he goes, ‘Okay, baby.’ And it was like a couple having a conversation: ‘Can you get me that from the fridge? Bring me the ketchup.’ ‘Okay.'”

“And they just coexisted and evolved and it worked,” he said, referring to the couple who got engaged last year after dating for two years.

Rex continued, “And no ego. They’re both very cool people.”

He also praised the Big little lies Star about her directing skills, mentioning that Kravitz’s experience as an actress helped her.

“She knows how to communicate and she knows very, very well how to take care of us. I was pleasantly surprised when I saw the film,” admitted Simon Rex.