When the little boy comforts Merlin the Magician, the balloon he is holding appears and disappears depending on whether he is shown from the front or the back.
When Mrs. Cassin goes to visit Apollonius to have her future told, the barker's voice twice states the price as "fifteen cents." However, both the sign and Apollonius himself state the cost as "five cents."
When the Abominable Snowman turns around to walk off the stage just before the circus starts, the hem of the costume's zipper can clearly be seen going down its back.
When Merlin first appears to Ed outside the tent a pipe at the base of the tent emits a cloud of white smoke so Merlin can "magically" appear. It continues to give several little spurts of smoke after he appears and while he is talking to Ed.