Continuity mistake: Before Beans the Cat puts the cat and dog into the piano, you can see there is an empty flower pot on the grass by the window. But when Oliver Owl sprays Beans with ink and he falls off the ladder, the flower pot has gone.
Continuity mistake: When Beans the Cat puts the cat and dog into the piano, you can see there is a book in front of Oliver Owl. But after Beans closes the lid, we cut to Oliver and the book has disappeared.
Continuity mistake: When Oliver Owl goes to the piano, he puts his bag of candy on the side by the keyboard. But after Beans the Cat has put the dog into the piano, there is now no sign of the candy.
Continuity mistake: When Oliver Owl goes to the stage to perform his piano act, there is nothing on his desk. But when Beans the Cat is watching his performance, look at Oliver's desk and you can see a book has appeared.
Continuity mistake: Before Little Kitty attempts to recite "Mary Had a Little Lamb", you can see there is writing on the blackboard behind her. When she makes her exit, the writing has disappeared, and when Ham and Ex appear, the writing is back again.
