Land Before Time 4 is called Journey Through the Mists. It's definitely better than the third one, but it's still a little all over the place. Like, Littlefoot makes friends with an old turtle named Archie, who drops out of the movie after ten minutes. And Spike gets a pet rat, who drops out of the movie after ten minutes. And Grandma gets a somewhat strange musical number. None of these things are bad, but they don't have much, if anything, to do with the main story.
I don't think I explained that well. Okay, how about this? There's a scene where the bad guys argue, because they're tired and they want to sleep. The next time, they're walking around awake in the middle of the night. No explanation is given, as to why they decided not to sleep. It's like their earlier argument was included just to take up screen time, and not because it's relevant. That's what a lot of the movie feels like. Things keep happening, and they're somewhat entertaining, but they don't feel super necessary or even all that thought out.
The story is that Grandpa Longneck is dying from a mysterious disease. Littlefoot has to find the golden night flowers, to save him. Also, Littlefoot gets a love interest, a girl named Ally who looks EXACTLY LIKE HIM. Ally is shy and doesn't like Littlefoot's friends, but eventually she comes to realize they aren't so bad.
Our heroes sneak out into the dangerous outside world, for the third movie in a row. I swear, they spent the first movie getting into the Great Valley, and they spend every out movie trying to get out.
The villains of the movie are introduced rather late. They're a bird and a crocodile, who constantly insult each other. The musical number is pretty good, but after the fifth or so scene of the villains trading insults, I got a little bored of them. There's also the problem that the villains constantly switch back and forth between "legitimate threat" and "goofy non-threat". That makes it a little hard to take them seriously. Like...here's what happens in their final scene. "Oh no, the bad guys found our heroes! Wait, that was just the setup for a joke. Oh no! They're going to eat Petrie! Wait, that was just the setup for a joke. Oh no, they're going to eat Ducky! ...I don't need to pay attention anymore, because I know it's going to end up as a joke."
This is also the movie where Spike talks for the first time! He shouts, "Ducky!", which wakes her up and saves her life. (And results in the bad guys getting whacked on the head multiple times.)
The movie ends with Ally going away. The narrator promises that Littlefoot will see her again someday, but that's another story. The narrator LIES, because she does not appear at all in the next ten movies.