Fridge Horror: In return for letting it snow in Southtown, Heat Miser demands that he be allowed a day of warm weather at the North Pole. Didn't spending a day in Southtown cause Vixen to become terribly ill? Now all of Santa's reindeer are going to be exposed to that climate.
Another bit of Fridge Horror that's more of a Fridge Tear Jerker is this notable difference between the Miser Brothers' songs. Snow Miser's song goes "Friends call me Snow Miser", while Heat Miser's equivalent lyric is "They call me Heat Miser" Is a Green Christmas so unpopular that Heat Miser doesn't have any friends? That's kind of sad. No wonder he's always angry at his brother.
Fridge Brilliance: The original 1974 special had Snow Miser and Heat Miser explicitly say that they are step-brothers, but the spinoff/sequel "A Miser Brothers Christmas" shows a flashback that depicts them as being fraternal twins since infancy. This may seem like a continuity error, but when you remember that the Miser Brothers hated each other, it becomes possible that the Miser Brothers simply hated each other so much that they pretend that they are not really related. Such a thing is not unheard of in real life cases of sibling rivalry.