Corrected entry: In the movie the kids know who the Cosby Kids are and the parents do not, yet it should be viceversa since the adults would be the generation who watched the show as children.
Corrected entry: When the whole gang is at the party and Albert and the rest start dancing, we hear "Hey, hey, hey" being repeated, however sometimes Albert's mouth doesn't move, even though he is the one who is singing it.
Correction: You don't exactly have to move your mouth to say "hey hey hey". I've tried it, the only visible thing you need to do is keep your mouth open.
Corrected entry: The paint is scraped off of Bucky's pants because Old Weird Harold knocked him over. However, this is after Old Weird Harold has overcome his clumsiness, so he should have been able to prevent hitting Bucky.
Correction: Harold did not knock into him, he pushed him with his foot down the rail.
Corrected entry: Fat Albert and his friends can't go back to their world immediately because their show is over, and it won't be on again for a few days. If their show is over, how can events in-between the episode at the beginning and the episode at the end occur such as Russell being tormented by the bullies in the junkyard? Fat Albert even says that his world needs lines and writers for these things to occur.
Correction: We don't actually know what a cartoon character does when the show is done. It's quite possible they have adventures that never aired. There is no way to say how it all precisely works and therefore no way to determine if it is a mistake or not.
Correction: And as an adult would you really believe, or would it even occur to you, that the cartoon characters that you watched as a kid generations ago, have suddenly become real humans, jumped out of a TV, and started making friends in the real world?