Continuity mistake: When the alley cats leave the abandoned house with their broken instruments, it shows Billy Boss behind Scat Cat and Hit Cat behind him. When they are shown on the fence, their silhouettes show Hit Cat behind Scat Cat and Billy Boss behind him.
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