Ed Helms and Christina Applegate may be the stars of "Vacation" -- but when original Griswolds Chevy Chase and Beverly D'Angelo arrived on set for three days of shooting, they were decidedly humbled.

"They [were like] royalty on our set. I mean it's like, the king and queen walked on and everyone was like, 'They're here!'" said Helms while promoting the film at CinemaCon. "It's like, it was a dream. A dream come true. And they couldn't have been more psyched and fun and playful. And aside from being fun, for all of us working on the movie it was just such a great affirmation that they wanted to be a part of it and were supportive."

So how is Rusty (Helms, a.k.a. the all-grown-up son of Chase's Clark Griswold) like his dad, and how is he different?

"Rusty is like his dad in that he's optimistic and hopeful and loves his family and wants his family to be close. He's unlike his dad in that he looks a lot more like Ed Helms than Chevy Chase," joked Helms.

Added Applegate: "Sweeter, a little bit more humble. He has a harder time kind of rallying the troops, you know? Especially in the first one, Rusty was with pops in that one, too. It was like, 'guys, we've got this!' And there's a lot of...confidence, and with Rusty there's a little less confidence about how things are gonna turn out."

For more from Helms and Applegate, including their favorite moments from the original movie and what it was like working with Chris Hemsworth and Leslie Mann, click on the video above.

"Vacation" hits theaters on July 31.

A former contributor to sites including MTV's The Backlot and Bloody-Disgusting, Chris Eggertsen worked in film development before indulging his love of pop culture writing full time. He specializes in horror, the intersection of social issues and entertainment and Howard Stern. He's on Twitter @HitFixChris.