Audio problem: At the illegal fight, as Castor and Oxheart get ready to fight, Oxheart's mom says "Don't kill him. Just rough him up a bit." you hear the lines, but her mouth isn't moving.
Audio problem: As the group approach Bluto's boat at Scab Island, Pappy is cranking a siren. A couple of seconds later, it sounds again, but he isn't touching it.
Audio problem: At the beginning of the fight at Rough House's, after Popeye says "Enough is enough", it looks like he elbows the two nearest guys. If you look closely, they react a split second before the elbows get them, and the sound completes the illusion. Also, the last guy Popeye is punching in the face is moving just out of sync with the punches. The sound is like a punching bag, but his head is recoiling just a split second out of time.
Audio problem: After Swee'pea is safe and as they reach out to bring him in, the Undertaker is saying "Hoopla! Hoopla!" but his mouth isn't moving.
Answer: One, Bluto is a bully and threatened him, after all his name is Wimpy. Plus he most likely offered to buy him a hamburger, which he would have paid next Tuesday.