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

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).