I'm willing to bet a lot of people coming into this series fresh feel the same way you did. I know I would have. Recognizing a number of the characters changes everything about this episode. This episode was largely fanservice to the manga readers or fans of SHAFT's referential and parody humor.

There are a lot of things given such short screentime in this episode that unless you were familiar with the characters, you would never have even caught. Notably, one of the shots of Mina during the panel show. There is no frame of reference for it unless you already know.