Continuity mistake: When the butler takes the mother and kittens to be abandoned in the countryside he is on a motorcycle and sidecar combination. During the trip the sidecar changes from one side of the bike to the other and back again. Also, when the sidecar separates from the motorcycle when the dogs are chasing Edgar, the wheel on the sidecar switches sides regularly as well.
Continuity mistake: When the male kitten plays the piano for his singing sister the painting kitten starts to join him. His paws are covered in paint. During a brief scene change you can see that the colour of the paint on his left paw has changed. Also he only has two colours of paint on him, but minutes later the keyboard is covered in all colours of the rainbow.
Continuity mistake: The kittens fight and a candle falls on the floor. The candle is part of the moving parts against the fixed background (decor). In the following shot the candle has become part of the background and thus changes colour and shape. In the next shot when the cats walk away from the area where the candle fell, the candle has disappeared.
Continuity mistake: The painting kitten (in the beginning of the film) steps on a tube of blue paint and squirts a bit that ends up on the floor. Minutes later the colour of the blob on the floor has changed to red and a few moments later the paintblob on the floor has vanished. During the 'paint' scene several tubes near the palette also change colour and position.
Continuity mistake: During the song 'Thomas O'Malley', Thomas jumps on the tree and shakes one of the branches to make the petals fall on top of Duchess. Just before they hit the ground, a whole bunch of petals appear on the ground out of no where and some of the petals that were falling to the ground disappear once they hit the ground.