Seeing the photo of JTT on Katy's make-up mirror that I gave her. 
Seeing the Katy Hudson videos of her playing a guitar (which movie researchers found thru my website).
"This moment... is my childhood dream... come true."
When gramma says "oh... okay..." after Katy tells her she thought she'd dress up.
When itty bitty Katy sings "beside her" (from 'God Bless America')... lol... that face... YAY!
"She just did it... COMPLETELY... HONESTLY!!!!"
"Controversy, oohh!"
Mia saying, "So she's basically the same!"
"So I stole all the files! I stole all the Katy files!"
ET... "For you I'll risk it aaalllll.... AAALLLL!!!!!!!!!"
When Katy introduces Glen Ballard and how important he was in where she is today. 
And an extra that made me fly is when she is driving thru Santa Barbara before they show her arriving at Gramma's house in Vegas.
this!, also i have always loved that ET part and listening to it live, omg, epic!!
i also still get excited when i see people i know in the movie lol, and the part where i appear for like 5 seconds while she's singing peacock n_n