Other mistake: In the beginning, when Maui is about to steal the heart of TeFeti, his back tattoos. On his right side, you get a glimpse of the tattoo of TeKa hitting him and him loosing his hook. He shouldn't have that tattoo since it hasn't happened yet.
Suggested correction: He has the tattoo in that shot to represent when he first stole the stone and fought Te Ka for the first time.
Te Ka only exists because he steals the stone as it's the island with no heart.