Approximately 00:43:46 into the film, at the beginning of the Fair Folk scene ("King Eidelleg and the Fair Folk"), when the little fairies have seen our heroes come down the whirlpool, the following line is said:

"I bet they wake up soon."

Well, it is clearly the boy fairy in blue robes talking, but notice him, in this line, his mouth is closed. Then notice that it is the girl fairy in pink robes that is moving her mouth, although this isn't her voice.