During Teen Gohan's special interaction with Pikkon, Gohan will say "I'm ready. You're so much like Piccolo." although the subtitles say "P-Please!" rather than what's said which is "I'm ready."
It's possible to glitch inside The Lookout. If the player picks any character that knows instant transmission, goes down to the bottom of the Lookout and uses instant transmission while the opponent is in the right spot, the player will be moved inside The Lookout.
As Semi-Perfect Cell, by backing up against the wall of the cave stage and performing your ultimate attack when the opponent is in close proximity, you will glitch out of the map and be out of bounds. This is due to the fact Semi-Perfect Cell's Ultimate (Super Big Bang Crush) has him relocate up in the sky to do his ultimate.
Teen Gohan in all of his forms will say "All right Piccolo!" for his opening battle quote to Goku and Krillin. In the first game he would just say "All right" to Goku and Krillin. This mistake was fixed in Ultimate Tenkaichi by cutting off the word "Piccolo" at the end of the Sentence.
One of Gogeta's random opening battle quotes is "I am neither Goku nor Vegeta, I am the man who will defeat you.", but the subtitles say "destroy" rather than defeat.