We have societal norms about it, maybe. But there are certainly no explicit rules about this, and the societal norms about lying are already pushed to their breaking point when you walk in to a movie theatre.
Rule and norm are synonymous, IMHO. What is the difference? What makes a rule explicit? Do you mean laws? Law itself is often rather abstract, does that still count as explicit?
I think there are specific laws about fraud. In film they can claim artistic license, though.
We have societal norms about it, maybe. But there are certainly no explicit rules about this, and the societal norms about lying are already pushed to their breaking point when you walk in to a movie theatre.