A lot of the Vietnamese, Laotian and Cambodian folks who made it out came to live right here in central California.
I knew several professional people who were lawyers and engineers and doctors. They managed to get out in advance by buying marriages to American citizens.
For a very small fee you could convince some citizen to marry you long enough to get you into the country, and then people would just ignore that it ever happened.
Legally those people were now bigamists, but with no complaint there was never any prosecution, or even investigation of the matter as far as I can tell