Why does this episode start out with ponies pulling the train?

The buffalo were cool. It's a shame they never made another appearance.

Salt as a metaphor for alcohol.  I can see why they never got away with that again but it was funny.

Then there's the cartoon logic of the pie fight. Well, I guess they could be meant to trip the buffalo up and blind them. Hot pie in your face really isn't funny.

So the solution was to chop down some trees, making Applejack bringing another one pointless. And why didn't they just dig up the trees and she takes them back? Oh well, cartoon logic.