"The whole movie was inspired by her," Rodriguez tells ET. "When I was making 'Machete' with her she showed up on the set, brought her baby and the baby's diaper had exploded so seeing her all dressed up in heels kind of looking like a spy already, I thought oh my gosh, if she was a spy on a spy mission and she couldn't find a babysitter, that would be a really great image for a spy kids movie. I mentioned it to her, and two years ago we started writing it."
Alexa Vega says Robert's decision to bring back the pint-sized crime fighters was a "shock." "He called the third one 'Game Over' for a reason," explained the actress, who played the role of Carmen for three films. "But to come back is a happy/ sad moment because we are passing the torch to new kids."
The film's new cast consists of Jessica Alba and Joel McHale as parents to Rebecca (Rowan Blanchard) and Cecil (Mason Cook). Alba plays a retired secret agent raising a new baby and struggling to win over her twin step kids.
Watch the video to hear more from the cast on their transition into the newest generation of 'Spy Kids.'
'Spy Kids: All the Time in the World in 4D' comes to theaters, August 19.