What are consequences for passenger fleeing the scene of an accident?

This is hit and run and can result in jail time. If someone dies it can be man slaughter as well.

Being a Passenger Fleeing the Scene of an accident with injury is a felony.

Another View: Although it seems a little strange and might lead the investigating officers to look further into the circumstances, I am not aware of any law which requires that a PASSENGER in the vehicle(s) involved remain on the scene.