Continuity mistake: When Ash and Misty wonder what happened with Brock's internship with Professor Ivy, the rectangle with the button on Misty's shorts goes from blue to yellow. Also, there is moulding in the living room, but in the next shot, it disappears. (00:03:45)
Continuity mistake: When Brock is next to Ash at a cabinet, the right support of the table goes from being a darker brown than the top of it with it being not past the oven to being the same brown with it past it. Also, the number of rows of tiles before the window goes from four to five. (00:02:39)
Answer: He is a good guy but just found himself in a bad situation when he worked for Lysander. He didn't want him to harm Ash and his Pokémon when he was trying to get the special bond between Ash and his Greninja to work. He does leave Lysander and go back to being a good person.