I don't really think Utakata was rendered unconscious by those rockets at all, I imagine the fight was just cut out to not show Pain's powers. If you look at the rubble he's in, in comparison to the other explosions, it isn't near the same at all, so I'm fairly certain he wasn't incapacitated by those rockets.
i agree, they probably didnt want to show his powers.
I do find it quite weird that he had so much control over his bijuu though, seeing as he didnt seem to communicate much. He didnt really even seem to like it or have been with it too long. But, maybe it was how his master sealed it in him which allowed greater than normal control.. :-/ Anyway, its a filler, so cant expect too much from this.
The preview shows Jiraiya's death being revealed to Naruto, and Naruto's subsequent mourning.
With regards to Utakata vs. Pain, there's no way they could have animated a legitimate battle without revealing more of Pain's abilities (especially God Realm). That much should have been obvious to anyone current on the manga.