The baggage car, in which Sylvester and Tweety are riding, changes positions during the ride. In closeups, it will be either third, fourth, or fifth behind the engine. In long shots, it's not there at all. Only coach cars are seen.
In closeups, the train's engine carries the No. 651 in some shots, and No. 814 in others. In some long shots, it has no number.
The coal tender has at times the No. 99 on it, or no number at all. Other times it has the letters "S.P. & Q.R."
In long shots, the coach cars sometimes can be seen with the letters "S.P.Q.R." on them. In closeups, this changes to "SouthEast & Western."
When the bulldog makes its appearance, Sylvester's carrier is right next to its kennel. This close proximity allows Sylvester to reach out and hit the bulldog with an umbrella when the dog starts to bark at him. But suddenly, Sylvester's carrier is no longer next to the dog's kennel. Suddenly, his carrier is at the other end of the train car, which sets up the next gag. The train then goes up a hill, causing Sylvester's carrier to slide downhill toward the bulldog's kennel. When the carrier slams into the kennel, the dog punches Sylvester, throwing him (and the carrier) back uphill toward the opposite end of the car, where it once again slides back downhill toward the dog in his kennel. The punch and scenario repeats. But then just when Sylvester is sliding toward the dog a third time, the car levels out. But the next scene is of the train still going uphill before reaching the hill's summit. The train then goes down the other side of the hill, and the dog and its kennel now slide toward Sylvester. The joke now reverses as the dog just sticks his fist out of his kennel and allows his downward momentum to punch Sylvester as the kennel slams into Sylvester's carrier.
It seems a bit pointless Tweety being kept in a cage that he can leave to pull the emergency stop cord etc.