Audio problem: When everyone is running after the police car, we hear Robin shout "Hey guys! Joey, c'mon!" but her mouth is shut. (00:14:05)
Audio problem: When Junior is riding his motorbike around, screaming "they hurt me, ma," in many wideshots we hear him yell but his mouth is closed. (00:55:20)
Answer: He simply just snapped. He definitely looked angry before Joey even started talking to him, and said how he hated being there...and he already had an axe in his hands...he just lost it, and took out his anger and frustration on Joey.