Audio problem: In the Knight Bus, when Shrunken Head says, "Yeah, take..." in the front shot, his mouth, cheek and jaw move as he speaks. As he continues, "...it away, Ernie! It's going to..." in the back shot, his mouth and jaw do not move at all, yet when he says, "...to be a..." his mouth and jaw move as usual.
Audio problem: As Sirius, the dog, drags Ron towards the Whomping Willow, Hermione and Harry chase after them. When Sirius actually backs up into the hole below the tree trunk, Ron begins to shout, "Help!" In the next shot, as Harry starts to stretch his arms forward to dive down, Hermione runs behind him and visually she shouts Ron's name, though there is no sound heard.