Is it illegal to leave the rear entry door open in a clup that sells alcoholic beverages?

Its certainly dumb... because that is the least watched door in the place with easy acces to inventory that can easily be stolen without being seen. Or for people to sneak out of without paying their bill / tab..

If you know so much, as evidenced by the fact that you gave smoothy a negative, then why are you here asking?

But no, it's not illegal... but you knew that already.