the "error" is not really an error. it is a Notice. it means that you have code that is referencing variables that don't exist.
it may be that the variables being referenced don't get created when the page initially loads, but do get created at another time.
the Notices don't show on the live server because the error level on the live server does not show notices.
send a copy of the pages so i can see the code at those lines to tell why the Notices are happening and whether or not the are problems or can be ignored.