This was a pretty good episode with a solid storyline.
Having the episode take place on a train doesn't seem like that exciting of an idea, but the writers pull it off. Gadget, thinking he is a MAD agent, chases Brain from car to car. He even follows him up on the roof and has to avoid being smashed by a tunnel and a bridge.
Gadget makes it into Dr. Claw's headquarters, and he actually stands face to face with the villain, but he has no idea who he is.
One scene is a classic Superman moment. Gadget saves the train from a destroyed bridge by using his body as a railroad track.
The only downside to the episode is that, as in the previous episode, Dr. Claw is not voiced by the usual actor. He isn't as threatening.