My husband manages a movie theater, and my cousin owns one.  Neither has ever
talked about having problems with patrons bringing in food.  It is dark and
they just don't see or care!  They worry more about the hundreds of customers
who come to the manager to complain about the movie not being good, even
though they sat through all but 10 minutes of it, and want their money back!
And if someone DID have food and they questioned it, the minute they heard
about the food allergies they would say, "Fine, no problem!"  And the younger
employees who work there?  Food taken into a theater from home is also
something FAR from their minds!    Any place that DID have a problem with it
should not get our business.  So I say, "bring your food and enjoy!"