Recycled Soundtrack: Aside from the new compositions for the game, the entire soundtrack is justifiably lifted from Persona 3 and Persona 4. It even makes use of the boss theme from Persona 3 Portable's Female Protagonist route!
Schedule Slip: In Europe, the game was originally slated for a September 2012 release. European distributors Zen United/PQube were finally able to confirm a May 10th release in the middle of March 2013. In comparison, Persona 4: Golden, the Updated Re-release of the original Persona 4 for Vita, was released in February 2013 in Europe.
Technically, this applies to everyone in the playable cast as the Malevolent Entity masquerades as their shadow during Story mode. Except for Yu, but he instead runs into his "Shadow" during his Arcade mode. And of course, this comes about through the ability to have a Mirror Match, as this is a fighting game.
Karen Strassman as Nanako Dojima and Aigis. Subverted, in that they never speak to one another.
Ryotaro Dojima was considered as a playable character (instead of a Persona, he'd summon Nanako, giving the impression he would have been a Joke Character), but Atlus shot the idea down.
Akihiko's initial design for the game was, in the words of Zen United, similar to Jason Statham in The Transporter, implying Soejima may have planned to give him a design similar to his Trinity Soul appearance. However, the director felt a 'wild man' was needed, and influenced Akihiko's drastic change in appearance.
Aigis was intended to have a braided ponytail in her new design. That went to Fuuka in the end.
Going through the sound test in Gallery mode shows some unused lines for each of the characters, including the Investigation Team calling out their Ultimate Personas, and the Shadow Operatives calling out their own initial Personas. Obviously, the unused Personas were considered for the game at some time, but ultimately failed to make it into the final product.