I agree with post #2,A Midsummer Night's Dreamdefinitely has dark undertones. The treatment of Titania is the worst in the play and still makes my skin crawl when I re-read it. It would be so much simpler to just say that the play is all light-hearted and in good fun, but rarely did Shakespeare leave anything to chance in his works.
At first experience, one enjoys watching or reading the hilarious miscommunincation, deception, and other goings-on in Shakespeare's "A Midsummer Night's Dream." It is a comedy and should be enjoyed as such. However, deeper themes that come to mind is bullying and the blatant disregard for a person's feelings (like Demetrius being so rude to Helena to get her to leave him alone). Step a little further into the darker depths of human baseness and the word "bestiality" comes to mind. But that's as far as I'll go thinking about that concept. Other dark themes could be domestic abuse. The way Oberon treats Titania is unacceptable. Oberon proves to be a master manipulator by drugging his lady and playing such a sick trick on her. That's definitely an example of an unhealthy relationship that when laughed at in a comedy might give people the idea that it is ok to treat someone like that.