I was just curious, is there any set amount of "overtime" an employer can require an exempt employee to work? Say 50 hours? Example, I am a warehouse manager and was hired in by our Area Manager. At the time of the private interview with him I was told that 45 hours are what is required. Fine, I had no issue with that as I generally work 45-60 hours a week anyway.
Several weeks later, that Area Manager was terminated. We have an "acting" Site Manager now that is telling me I left early a few days the previous week and has used this to write me up for corrective action. I put in my hours and work my job to the best of my ability, one of the days in question I had come in at 5 am to unload a truck that had equipment we needed badly on it. I left around 2 pm. The following day I worked 8 hours and left to pick up my son, one of the reasons I took this job was that I was told during the interview that I would work Mon-Fri. I understand that the employer can change their staffing hours.
My base question is this, how MANY hours can they force me to work as an exempt employee?

As many as they like.

The maximum number of hours either an exempt or non-exempt employee can be required to work in a single week is 168.

I've been told that California law prohibits working for periods longer than six consecutive days. Even here you need to rest for one day.

That is sort of true. You are talking about CLC 551-554. There is a one day in seven rule, but there is a rule that says "Nothing in this chapter shall be construed to prevent an accumulation of days of rest when the nature of the employment reasonably requires that the employee work seven or more consecutive days, if in each calendar month the employee receives days of rest equivalent to one day's rest in seven." Arguably the rule is more like a cannot work more then 24 of every 28 days if you look at the entire set of CA labor code.

http://www.leginfo.ca.gov/cgi-bin/di...0&file=500-558

Misssouri has no caps on work hours. California has some (72 hours in a week, but only for some jobs, not all). Maine won't allow anyone to work more than 80 hours of overtime in any two consecutive work weeks. That could be 40 hours this week, 120 hours next week and 40 hours the following week.

There are some industry specific limitations, some federal (truck drivers, pilots), some state specific (nurses in Maine).

And then there are the one day in seven states (few).

Unless your job is specifically laid out in law or a contract with a cap on time worked, you get to work all the time that the employer demands.

Where can I find the reference for the 72 hour limit in California?

It's probably in the applicable Wage Order.
http://www.dir.ca.gov/iwc/wageorderindustries.htm