Continuity mistake: There's a scene where Arnold is talking about saving the neighbourhood, while Helga is on the roof of a building talking to herself. Arnold is in the street, and there's a man in a white tank top standing in front of him. In another shot, the man is standing behind Arnold, and Helga shoots a plunger at his head. Then in the next shot, the man is back in front of Arnold and his head doesn't have the plunger on it anymore.
Trivia: Craig Bartlett, the creator of the nickelodeon show that the movie is based on, is the voice of Murray the bus driver, and others, in the movie.