Found out about this pretty recently, but in the Preview demo of Sonic Adventure 2 there is a particularly chilling unused voiceline of Sonic screaming in pure fear and pain.
While it is technically used for the Biolizard's roar, it is so heavily filtered that you can't hear it.
During Covid I got a PS4 copy of this game after not really enjoying the PS3 copy of Vanilla a couple of years prior. I remember being at my lowest and this game getting me through it. Legit crying with joy while sipping a vodka and coke. It was a bad time but this game helped!