These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
YMMV: Much Ado About Nothing
Alternate Character Interpretation: It's very easy to imply, through the body language of the actor (especially in the film adaptation), that Don John is interested in Hero, which actually makes sense, given his actions.
Additionally, the 2011 stage adaptation made it clear that Don Pedro was in love with Beatrice.
Ethnic Scrappy: A 2011 production of the play by Washington DC's Shakespeare Theater Company set in 1930s Cuba renamed the characters Hugh Oatcake and George Seacole Juan Huevos and Jose Frijoles (Spanish for eggs and beans) before Latino organizations protested (keep in mind the play did not Hispanicize Don John's name into Don Juan). Furthermore, the play featured a Translation Convention where the only actors in the play who spoke with Spanish accented English were those playing the rustics and the servants while the main characters spoke eloquent English.
Moral Event Horizon: Arguably, the way Claudio chooses to call out Hero for her "infidelity." He did so loudly, in no uncertain terms, and in a public place. By the standards of the day, Hero's reputation would have been ruined forever, as would be her family's, and a pall of doubt would have been cast over anyone connected to her. Her virtue impugned, she never would have been able to marry; Hero likely would have been forced into a nunnery by her family. No matter how naive he might seem, there's no way Claudio didn't know this when he called her out.
Tear Jerker: Provided the actress playing Beatrice knows what she's doing, and has a Benedick who knows what he's doing, Beatrice's monologue begging Benedick to kill Claudio (or at least challenge him) is virtually guaranteed to leave a sizable portion of the audience close to or actually in tears. The 2011 stage version has an exceptional example.
Values Dissonance: Hero is delighted to eventually get married to the Jerkass who accused her of being a whore on her wedding day. While she was at the altar. In fact, in the BBC's recent setting update of the play in Shakespeare Retold (starring Billie Piper as Hero), she actually doesn't take him back.
This one really depends on the way the role of Claudio is performed- in the vanilla script he seems to be more mistaken than malicious.
The David Tennant/Catherine Tate version (set in the 1980s) has an addition, after the scene at Hero's supposed tomb, where Claudio returns to tomb, gets wildly drunk, and is about to commit suicide, when Hero sees him and steps out of the shadows to stop him. Claudio sees her, thinking (most likely) that he sees a ghost, and passes out. That goes a fair way to making Hero's acceptance of Claudio, even in a modern setting, palatable.
Why Would Anyone Take Him Back?: Branagh did a good deal to avert this by trimming out most of Claudio's more unsavoury lines, giving him a clear view of "Hero" and Borachio, showing his genuine remorse and subsequent atonement, and casting him as a baby-faced Robert Sean Leonard.
What the Hell, Casting Agency?: Exactly why did Keanu Reaves and Denzel Washington play Don John and Don Pedro, who are, in fact, brothers? (Well, half-brothers...)
Values Dissonance: Several in moving Shakespeare to the modern day, most notably the plot-driving point of the scandal of a lady not being a virgin on her wedding night (saved in the particular by the extreme of her cheating the night before the wedding). See also Lampshade Hanging above.
Whedon chose not to excise Claudio's line "I'll hold my mind, were she an Ethiope" and instead draw humor from it by having a black woman stand right behind Claudio giving a Death Glare while Benedick watches on with a handless Face Palm.