The Great Gold Robbery, Part 3 - S1.E15

Underdog is still confused and frustrated trying to find Sweet Polly among all the balloons, so far only coming across the record players Riff Raff's gang implanted in the balloons. But then Sweet Polly's balloon springs a leak and is plummeting towards earth toward a hungry alligator. Underdog then finds the real Polly in trouble and saves her from danger. Meanwhile Riff-Raff and his gang take over a railroad station, planning to throw the switch so the gold train Underdog was guarding will collide with another train.