I'm pretty sure that, back in my HR days, I read a law that says you can't schedule an employee less then 8 hours between shifts without paying overtime. Now that I've tried to find it again, I'm coming up blank. I know laws change all the time so I'm wondering if anyone can point me in the right direction. Is this still the case? If so, can you tell me what I can refer to? Any help you can send my way would be appreciated!

It depends. Overtime is based on the defined workweek, which must begin at a date/time certain and, in California, the work day, which is just a smaller increment of the workweek. Each 24-hour period, starting from the date and time of the defined workweek, stands alone.

My recollection is that an hour's additional pay must be provided when an employee works a split shift when the time between shifts is 2 hours or less.
Sorry, I can't find the Wage Order at the moment. I'll check some more later today.