Other mistake: When Cory and Shawn are auditioning for "Guys" and they're talking about the first person they pick, Cory says,"He's shorter than me and..." but after they pick both guys and he's talking to them, you can see that Cory is the shorter one.
Revealing mistake: When Cory and Shawn are holding band auditions, if you watch the guy that is shredding on guitar, you can see that although he is moving his fingers all over the fret board, his picking hand remains motionless, showing that he isn't actually playing and the sound was added in post production.
Answer: I learned the answer to this one today. It is "Tree of Life" by Garé Barks.
Phaneron ★