In what episode does Kakashi thinks Naruto is his sensei Minato? Not the one in shuriken training, but the one on battlefield. The song My Name started playing and I remember the scene being so badass.
The episode is #329 of Naruto Shippūden, titled "Two-Man Team". It's manga equivalent is Chapter 571, "Tailed Beast Mode!!". The scene you're referring to is at 08:05.
Kakashi mistakes Naruto to be his former sensei right after Naruto deflects the five Tailed Beast Balls with astonishing speed.
Here's the scene from the manga: