Now that you have watched Kenneth Branagh’s 1994 film version of Much Ado About Nothing, you should have noticed some important differences between the film and the play. For example, Branagh has changed the setting of the play from the urban environs of Messina and moved the action out to the countryside. This is actually a very significant difference. Remember that Leonato is the Governor of Messina. Therefore what is happening with the marriage of his daughter also affects his political life, and his livelihood. That, of course, impacts everyone in his household from the servants on up. In what ways might moving the setting of the play away from the physical seat of political intrigue and power have on the tone of the performance?

While it is possible to read Shakespeare's comedies with overlapping concerns of the political, the cultural, and the personal at play, Much Ado About Nothing seems to use the political context of Don John's disloyalty to his brother mainly as a precondition for the gathering and as another depiction of disloyalty.
Whether a director is staging in a theater, filming within Messina, or filming in the country, as Branagh does, it seems a stretch to say that the location of Messina would offer a lot more to the text. Branagh loves beautiful settings, and the broad panoramic vistas he includes early in the movie set a tone of playfulness and inconsequentiality to the war recently ended. It creates something of an inversion to the tone used in As You Like It, where the latter scenes in the forest offer more creative playfulness. In Much Ado, the opening half is filled with romance and frivolity and wit, while the second half tends to feel more claustrophobic as Don John's plot against Claudio takes effect.
The movie tends to offer darker and smaller spaces for the scenes in the latter part of the play to represent this smallness of spirit that accompanies the disloyalty and accusations against Hero. While Hero's slander might affect Leonato's reputation, it would likely not affect his power in the near term, though having an heir to his fortunes would be a matter affected by Hero's death or her sullied name.