All dates listed are in 2012. I have merely summarized the events and more detailed information can be found via the source links.
June 24: Advanced Screening Event
Some time before this date, Mitsuhiro Ichiki auditioned for an original character for the TV series. He was invited to the screening event as "a surprise voice cast member". However, at the event, he was informed that he was actually appointed "Head of Public Relations" for the series. The original character does not actually exist.
September 2: Twitter
The opening theme's composer, Hajime Kikuchi, sent rude tweets to well known voice actor and singer Momoi Halko. He decided to step away from the music group (eufonius), but it's unclear whether this was truly his own action or something "forced" upon him by the label.
Source: ANN and MAL
As a result (well, according to the animation studio, due to "production issues"), the opening theme was changed on the BD/DVD release of the series and for some of the episodes during the TV airing. This was probably the cause of the BD/DVD release getting delayed by a month.
Source: Two ANN articles: One and two
The linked ANN article for the screening event also mentions that Hajime Kikuchi may have made some tweets about that incident, but it does not mention whether they were apologetic or negative.