All a Bir-r-r-rd (1950)

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.

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 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."

Trivia: When we see the train during the opening credits, look at the carriages and you can see they have names of Warner Brothers staff on them: "Frizby" (Friz Freleng), "Hawley" (Hawley Pratt), "Ross" (Virgil Ross) and "Champin" (Ken Champin).

Trivia: When Sylvester slides open the door after being burned by engine's furnace, there is a crate with a label on it saying "From C. Martin Jones" - a reference to the Warner Brothers director Chuck Jones.

Trivia: When Sylvester slides down into the bulldog, who punches him and sends Sylvester into the wall, look in the background and you can see a chest with a label saying "From Friz Freleng, Pratt Falls." Friz Freleng is the director of this cartoon, whereas "Pratt Falls" is a reference to the Warner Brothers layout artist Hawley Pratt.