Continuity mistake: When Pluto rescues Dinah from the pond, he initially puts her on the gravel. In the next shot, Dinah is now on the grass.
Continuity mistake: In the scene where Sylvester tells the bulldog to be quiet when they are in their cages, you can see there is nothing behind them, but when we see the train about to go up a hill, we cut back to Sylvester and crates have suddenly appeared.