When Cool Cat tries to go to sleep, his eyes are still open and he has no eyelids, but when Butch kicks sand in his face, Cool Cat suddenly has eyelids to make his eyes look screwed up in shock, which could have been used earlier in the film.
Throughout the film, Cool Cat's tail goes from curved to straight, and even disappears a few times.
When Maria comes to visit Cool Cat, two cars are parked near the garage. When she comes out a moment later, both cars are gone.
When Cool Cat reaches out for his pen and paper, he accidentally drops a picture of himself and doesn't pick it up. In the next shot, it's in place again.
At the beginning, one newspaper headline says "Kids Loves Cool Cat." It should say "Kids Love Cool Cat."
Children can't really get arrested by police.
Butch just walks on Vivica and Erik's private property without security guards stopping him.
When Cool Cat talks to Butch the Bully's friends, a man walks out of a house in the background, spots the film crew, and immediately backs up out of frame.
A discolored line is visible down the screen any time Cool Cat and his mother are on screen at the same time. Two takes were clearly merged together. The production had only 1 cat suit.
When Cool Cat and Daddy Derek's perform "Cool Cat Likes to Rock and Roll", neither Cool Cat's microphone nor Daddy Derek's guitar are plugged in to anything.
Derek Savage's name is partially visible on the "Trolly the Trout" drawing when Cool Cat presents it to the camera as his own original work.
Butch the Bully's line "Boy I feel like picking on someone!" starts before the camera switches over to him.
At the start of the film, when the camera enters Cool Cat's house, the shadow of the camera operator and a crew member walking behind them are visible on the wall.
In some closeups, the camera is reflected in Cool Cat's eyes.
Maria is implied to be skipping from her house to Cool Cat's. On her way inside, a blanket is on Cool Cat's front lawn. The movie says Maria put it down, but it was clearly there before she got there.
Cool Cat supposed to be a kid, but he drives the "Cool Cat Convertible" before going to the Hollywood Parade alone without adult supervision.
At the school, Daddy Derek and the teachers tell Cool Cat and the Kids that they worked together and prevented a bad situation, and that they saved the day. The film never shows or explains what they actually did.
Cool Cat and Daddy Derek go to Hollywood to sign up for the Hollywood Christmas Parade, then come back home without having done anything to sign up.
Cool Cat tells Maria and Mikey to always look both ways before crossing the street. Minutes later, Cool Cat runs across the street without looking both ways.
The police officers arrest Butch the Bully without being called or informed of his actions, and congratulate Cool Cat, who was chasing after him. Without context, Cool Cat could be the aggressor.
Erik Estrada reacts angrily when he sees Butch the Bully "kick sand in Cool Cat's face." In the preceding shot, Butch the Bully kicked the sand in a completely different direction.
When Cool Cat tells Daddy Derek he can't open the car door, Daddy Derek said that the lock was there for safety purposes. The car window was open and anyone could enter the car, which defeats the safety purpose.
When Cool Cat comes out of his house dancing and holding onto a radio, his tail gets caught on a bush.