Big Lipped Alligator Moment: Stella's song, "Come Fly With Me" in Wings Of Change certainly qualifies. Including sudden change in lighting and even background singers and dancers coming out of nowhere! Most of the songs are portrayed realistically (except Muru's in Wolf Quest, but he's a spirit so its justified), her's...not so much...
Broken Base: The fan base is divided over how good the sequels are and if they're worth watching. However, most do agree that as far as animated sequels go, they're better than most.
Draco in Leather Pants: Steele and Niju, despite being the Big Bad of their respective movies, are quite popular with the fanbase. Niju has the excuse of just being afraid of losing his home, Steele is a bit harder to justify. Still, doesn't stop plenty of fanfiction and fanart showing Steele performing a Heel Face Turn and Niju paired with Aleu.
Ensemble Darkhorse: Star from the first movie. Sadly, he wasn't in the sequels. Same goes for Kaltag and Dixie as well.
Besides Kodi and Aleu, Balto and Jenna also had other puppies (named Dingo and Saba in the credits); we only see them like in two minutes of the second sequel (there's not even any consensus on which of the puppies is supposed to be who!), and yet they are very popular in the fan base.
Moral Event Horizon: Steele is an arrogant blowhard, but when he deliberately sabotages Balto's team efforts to reach Nome and thus endangers not only them, but the dying children who desperately need the medicine being delivered simply because he was embarrassed by Balto trying to help his team and then forced to take it over as a last resort, he sails over the line into evil.
Nightmare Fuel: The fight with the giant grizzly is actually pretty violent.
Also Nightmare Fuel in that it was Diptheria that the kids had. Diptheria is actually pretty scary.
The closeup of the coffins the carpenter is building for the kids.
Ship-to-Ship Combat: Dear God, the fight between those who pair Balto's son Kodi with Dusty (who already has a love interest, according to the director of the second sequel and to her interactions with Ralph) or with Kirby is still going on!
Tear Jerker: Say what you will about Wolf Quest. The ending, where Balto and Aleu part ways over an instrumental "Someone Who Loves You", tugs on the heartstrings.