The song "Somewhere Out There". Even though the mice children aren't very good singers. They come across as a bit squeaky. Although it adds to the charm. The Narm Charm, that is.
The song would come off as less sincere if they hired some professional to sing it, as evidenced by the cover of the song done during the credits.
Tanya insisting throughout the whole movie that her brother was still alive. Unlike her grieving parents, she never gave up on trying to find Fievel.
Similarly, Tony takes it upon himself to look after Fievel, essentially becoming a big brother to him during his struggle to find his family. Bridget similarly becomes something of a sister-figure to Fievel once she hooks up with Tony.
Fievel and Tiger becoming friends, with Tiger even helping Fievel to escape the cats and later returning to help reunite him with his family. Not surprisingly, they all become fast friends with Tiger after he shows himself to be a good cat.
Fievel finally being reunited with his family at the end of the first movie is sure to move you to tears.
