Hmm...I haven't watch the episode yet but I have read the manga chapter in question.
I think the reason why that henge fox only had one tail was so that Sasuke would not see a Kyuubi henge. In the manga...Sasuke would have just thought it was the frog under Naruto's command transforming into a regular fox. But now, in the anime, Sasuke is seeing a frog under Naruto's command transforming into the Kyuubi form and you think Sasuke would wonder how Naruto knew what Kyuubi looked like. As we know, to the most recent chapter, Sasuke and Sakura are still not aware of Kyuubi being inside of Naruto. Sasuke seeing a henge Kyuubi would make him suspicious of Naruto, wouldn't it?
I don't know, that's what i think.