Continuity mistake: After Pongo spots Anita and Perdita walking towards the park, Pongo moves the time forward on the clock and he leaves the dial's hinged bezel open as he rushes to the door and barks, but when Roger checks the time on the clock the bezel is closed. (00:06:20)
Factual error: It is barely credible that a young Victorian woman like Elena would even think about wearing a goatskin miniskirt - exposing her legs in those days would be akin to walking about topless nowadays. Even if she did those bright yellow cotton knickers - gleefully visible in the scene in the beehive - are in no way from the 1860s. Her pants are a hundred years ahead of their time.
Continuity mistake: In the cabin when they are coming up with the idea to swap places, Susan has on white sneakers in the beginning of the scene when she is on the bed, and Sharon has on the black Mary Janes. Later in the scene, with no time to change shoes, Susan is seen walking around the cabin wearing the black Mary Janes.
Continuity mistake: The police that come to the aid of the professor are driving an older Ford when they approach than when they arrive to help. The car is a newer model in the later scene.
Character mistake: The registration number of the stolen van is GPW729 but every time it mentioned in the dialogue it is stated as GPW927.
Continuity mistake: When Sylvester sees the Daily Bugle newspaper, the front cover headline reads "Police Hunt The Cat." You can see the words THE CAT have nothing around them, but when we see a close-up of the newspaper in the next shot, inverted commas have suddenly appeared.
Continuity mistake: When Sylvester and the bulldog try to blow up the chain with some TNT, you can see the explosive has the wording "TNT" on it. But when the two take the explosive and put it into a hole, the "TNT" has gone. The wording reappears when the explosive falls out of the pipe.
Continuity mistake: When the Coyote tests his dart bomb, he lights it with a match in his left hand. But when he throws the dart bomb in the next shot, the match that was in his hand has gone.
Audio problem: As Tom and Mary exit a home that faces the town square, the sound of applause is heard even though almost all the townspeople are holding glasses of lemonade and nobody is clapping.
Continuity mistake: When Sylvester is pursuing Speedy on his motor bike, Speedy stops at the end of the cliff. But when Sylvester sees the cliff, there is now no sign of Speedy.