Except of training course we then pull back and see that they're just watching stock footage of the train on Tv. In "Grampa vs. Sexual Inadequacy", we see a montage featuring sizzling dogs rolling down a conveyor belt, a rocket taking off, etc. Subverted when it cuts absent to Bart and Lisa at the film theatre viewing a Stock Footage marathon, and thinking why their dad and mom have instantly despatched them to the cinema.