Continuity mistake: The thugs fall down the steps & land on the middle landing. You can see all of the steps & there are no puppies on them. In the next shot, all of the puppies are on the steps, just reaching the bottom.
Continuity mistake: Cruella goes flying off a cliff & lands her car into a snow bank. Her car goes half way into the bank, covering her windshield completely. But, in a shot from inside the car, you can see there is no snow on her windshield at all.
Continuity mistake: Rolly stops on the steps & is all alone on the steps. He then starts to run up the second set of steps. In the next shot, you can see the entire set of steps, but Rolly is gone.
Continuity mistake: We see Anita walking Perdita. She's wearing a light brown outfit and hat. But, a few shots later, as we see her crossing the street to the park, her outfit and hat are much darker, and remains darker for the rest of the scene at the park. (00:05:40 - 00:08:10)
Continuity mistake: The puppies are watching a western on T.V. One of the puppies (Patch) is biting a rug. After he says the line, "He'll get that yellow livered.", the light brown ring on the outside of the rug changes to light blue.