Revealing mistake: Near the end of the episode, after the Hulk jumps from the wooden crate, he walks around barefoot. But right after the pickup hits the car, we can see that the Hulk is wearing green shoes to protect his feet.
Factual error: The story takes place in Galveston, Texas. The geographical area is flat, but if you look closely near the last hulk out, there are mountains in the background.
Answer: The Hulk is accused of killing Dr. David Banner and Dr. Elenia Marks. After the lab explodes, McGee sees the Hulk emerge carrying the body of Dr. Marks, so he assumed the creature is guilty. It was McGee who caused the explosion. After following the trail of evidence of the Hulk to the lab, he hides when David and Elania arrive. In a darkened storage closet, he knocks over a bottle of flammable liquid. He confronts them, then is forced to leave by Banner, who says, "Don't make me angry, you wouldn't like me when I'm angry." When Banner reenters the lab, it explodes, caused by the Hulk when it went on a rampage trashing the lab, causing many electrical systems to catch fire, thus igniting the flammable liquid.