Continuity mistake: When the horse bites Edgar's coat-tails at the end of the film, in the next shot his coat is whole again - same error as when the dogs bite his pants.
Continuity mistake: When the movie begins Adelaide's gloves are grey, except for the brief shot when she steps off the carriage and they turn cream coloured.
Continuity mistake: When Adelaide is about to step off the carriage the box has string around it. A shot later it swaps to a thick pink ribbon.
Continuity mistake: Just before O'Malley jumps on the "magic carpet" truck, it plainly shows it has no crank, but after it stops, a crank appears for the driver to restart it.
Continuity mistake: When the cats are on the piano during the "Everybody Wants To Be A Cat" sequence, there is a sheet of music in front of the pianist. When we see the piano and the cats falling through the floors, the music sheet has gone.
Continuity mistake: When Edgar locks the cats in the trunk, the padlock closes on the left. But when Roquefort unlocks it, it opens on the right.
Continuity mistake: Throughout the film, the studs on the collar Duchess is wearing vanish and reappear.
Chosen answer: It is the style of the artwork. Similarly, it is not a mistake that each individual hair is not drawn, the eyes are not really proportional to the head, etc.
Myridon