• Dorothy is not muddy despite falling in the pig-pen. 
• Length of Dorothy's hair throughout the film. 
• The Lion's crown changes during ``If I Were King of the Forest''. 
  Dorothy loses the Tin Man's oil can when she chases after him, but it's back in her basket later. 
• During ``If I Only Had a Heart'', Dorothy's slippers momentarily disappear. [widescreen only] 
• The witch tells the flying monkey ``I've bugs ahead'', a reference to the deleted jitterbug scene. See also the Trivia entry. 
  The position of Dorothy, the Scarecrow and Tin Man after the Witch disappears from the cottage roof. 

A square block of wood to which the Lion's tail was attached is visible when the Tin Man is pulling on it while climbing up a hill. 
 

Juxtaposition of the adventurers when they're about the run out of the castle. 
 

The triangle theorem which the Scarecrow recites after receiving a brain is mathematically incorrect.