We don’t know that he does not have a passport and remember he was well planned out for this. He may be able to produce one if asked.
It’s her that does not have a passport and even that I’m not sure of. If he thought out every thing then say may have one too.
I go to Mexico a lot. They don’t tolerate illegals like Jerry Brown does. If an American is living there without a visa it only takes one complaint from one neighbor and you are gone or in a Mexican jail.
Mexico does not require a passport to enter; you need a passport to return. On the other hand, in the last few years there are cameras taking pictures pictures of cars/drivers/passengers before you get to the border. Most of the time the Mexican border people just wave you through while crossing. Mexico does require a Tourista card for anyone going more than 20 miles into the interior and they do enforce that pretty firmly with soldiers manning checkpoints. If they’re in Mexico, I’d bet they’re not very deep in Mexico—unless they know someone there to help them.