New lesson for any Union shoot - ALWAYS ask what sort of insurance they have. You may think they have insurance...it may say in your contract that the production has insurance...but this simply does not mean anything. I was badly injured on my SAG ULB shoot, and I learned that the only insurance they had was liability. So that means that anybody who was NOT onset and NOT employed by the production company was covered in the event of an accident. For instance, if we were filming a high-speed chase and we went off-course and hit an innocent bystander - they would be covered. But, if the lead actress injured herself doing a scene onset...she's out of luck.
Fortunately, we discovered that my injury was covered through worker's compensation through payroll services. Only myself and the SAG actors had this luxury. It was a stroke of luck that I was covered under this clause and had I not been, either the production or I would be out thousands of dollars in medical expenses.
Let that be a lesson to always check what kind of insurance your production has...