Continuity mistake: When Tweety says "That puddy tat - he mad at me!", you can see that the swing he usually sits on in his cage is missing, but in the next shot it is back again.
Continuity mistake: Throughout the cartoon, the baggage car where Tweety and Sylvester are riding keeps changing position. In close-ups, it will either be 3rd, 4th or 5th behind the engine, but in long shots it's not there at all.
Continuity mistake: The coal tender has the No.99 on it in some shots, or the letters "SP and QR" on others. Other times it has no number at all.
Continuity mistake: In the scene where Sylvester is sliding down into the bulldog who keeps punching him, there is a label on the side of the bulldog's cage saying "Warning Vicious Dog" that disappears when the bulldog slides down towards Sylvester.
Continuity mistake: When Tweety sees Sylvester in his carrier, you can see that Sylvester's carrier is facing straight but in the next shot it is now pointed at an angle.
Continuity mistake: In close-ups, the train's engine carries the No. 651 in some shots, and No. 814 in others. In some long shots, the number is missing.
Continuity mistake: Watch Sylvester's carrier in the scene when he is harassing the bulldog. You can see the carrier has a small front door and there are bars on the hole where Sylvester is looking out from, but when we see Sylvester later on, the door and bars have disappeared.
Continuity mistake: In long shots, the train cars can be seen with the letters "S.P.Q.R." on them. In close-ups, this changes to "South East and Western."
Continuity mistake: When the conductor swats Sylvester's paw after he attempted to grab Tweety, you can see the door to Sylvester's carrier is open, but when the conductor takes Tweety's cage, we cut to Sylvester and the door to his carrier is now closed.
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.
