Add anoher text box to the report, and set its Control Source to something
like this:
=IIf(IsDate([MyDate], Format([MyDate], "Short Date"), "See Below")
Replace "MyDate" with the name of your date field.
You may need to leave the MyDate text box on the report for this to work.
Just set its Visible property to No if you don't want to see it as well.