The conflict isn't age appropriate. Seriously, why are so many princess movies where the princess is trying to avoid an unwanted marriage? Not only is that difficult for a child to understand, but it seems downright inappropriate. Also, the "parent wants one thing and the child wants another" plot sends a very confusing message to young children - it makes it look as if the movie is saying, "do whatever you want, and things will turn out." This plot is best saved for older children.
The story's message is too easy to misunderstand. "Be yourself" can easily be misunderstood as "don't filter yourself, even to be polite," "follow your dreams," is so vague that it can mean virtually anything, and "never give up" could be misapplied and cause the child to think it's okay to beg for cookies, even after they've been told no several times.
The moral is unrealistic. In all too many childrens' movies and shows, the characters reach an idealized ending simply by behaving themselves. In Charlie and the Chocolate Factory, Charlie gets a factory because he was the only kid not messing off. In Cinderella, she got the prince because she was kind. And in so many stories, a kid wins a competition simply because they worked hard. The message is clear: Good things happen to good kids. So, what do you think kids who watch these movies will think if bad things start to happen to them outside of their control? I don't know how common this reaction is, but when I was little, I thought that I wasn't reaching my Happily Ever After because I had done something wrong.
The entire plot is built around a miscommunication between child and parent. Um, thanks for insulting the intelligence of parents, Hollywood. I would like to think that most adults are bright enough to figure out how their child misunderstood long before it becomes dramatic enough to cause the climax of a movie.
The use of excessive violence. Why in the world would you put life-or-death situations in a movie targeted at kindergartners? It's as if these filmakers are trying to traumatize their audience.
Using adult humor and innuendo. If you want to make the movie more interesting for parents to watch, spend time building up the characters and the plot, and add genuine humor to the story. When it comes to inappropriate content in children and family movies, I often hear the excuse, "It can't possibly hurt little kids, because they're too young to get it." You know what, little kids don't "get it" just yet. But normalizing this kind of content when our children are small will make them far less likely to recognize it as wrong down the line.
Overall, I think that we can stand to do better when it comes to the creation of kids' films, and especially ones targeted at extremely young audiences.