User blog comment:B214/Season 3 discussion/@comment-26439090-20150531050923/@comment-26345952-20150531054051

In episode seven it was mentioned by Rias that a televesion program wants Issei to appear, and as we all know that is the recording for Oppai Dragon Song. However, it was also said that this apperance (or interview) had to be after the game with Diodora, but in the LN it was actually before the game, in which cause the anime series be currently be without the Oppai Dragon (dosen't mean that it will be without one).

Plus I think it goes to what they were trying to do, to make that moment a little more serious and make proggresion with Issei and Rias's relationship. Though I would accepted it better if they didn't pull a "Pokemon first movie" on us (in case you're wondering, tears save the protagonist), but I diggres*(forgive my english).