Both victims, who have not been identified, were being treated at Orange County Global Medical Center. The hospital public information officer, Jeff Corless, said the couple's prognosis for their recovery is positive.
PHOTOS: Twin-engine Cessna crashes on 405, sending smoke and flames into the air
The small plane came down near the MacArthur Boulevard exit Friday morning, shutting down lanes for hours. Both directions of the freeway were back open to traffic on Saturday.
MORE: Small plane crashes on 405 Freeway near John Wayne Airport; 2 injured
Several people near the scene rushed to help, including an off-duty firefighter who's credited with pulling the victims out.
MORE: Off-duty firefighter, witnesses pull victims from 405 plane crash
The pilot made a mayday call shortly after taking off from John Wayne Airport, telling the tower he lost his right engine.
Luckily, no one on the ground was hurt and just one pick-up truck had minor damage when it was clipped by the plane.
The Federal Aviation Administration was investigating what went wrong.