Misery - When Moe picks up David Byrne after he is badly injured, Byrne asks Moe to take him to the hospital. When Byrne asks why Moe drove right past it, Moe ask him "have you ever seen the movie Misery?". The movie Misery is about a writer who is hurt in a blizzard and is taken in (then held captive) by a crazed fan of his work.
Back to the Future Part III - When Bart ropes Homer around the neck to save him from the beavers, it's a spoof of the scene in which Marty is roped by the hands.
When Cleanie comes in he says "My precious". The voice is a reference to the Lord of the Rings character Gollum. Cleany was voiced by Andy Serkis, who provided the voice (and motion capture) for Gollum in the films.
Bart calls Lisa "Crabby Hayes", a reference to the famed Western movie sidekick Gabby Hayes.
This episode was featured on The Simpsons Christmas Vol. 2 DVD, but it has nothing to do with Christmas, except for the scene in the beginning where The Simpsons are singing carols.
The sound of the footsteps when Clara is running across the log do not match her actual footsteps.
Water that Homer shoots at Flanders and then again at himself, freezes immediately, although it is liquid inside the hose. If it were that much cold outside, water in the hose would be frozen also, before Homer opens the valve.
Lisa claims Luke was her first crush, but her first crush was Nelson.