Thinking back to the Christmas episode. We had themes from:
It's Christmas Charlie Brown (Finn says he found that sad looking tree on the side of the road, and goes on and on about not losing the xmas spirit).
The Grinch (self explanatory).
Miracle on 34th Street (Brittany and Santa and an impossible wish that comes true).
A little Rudolph (singing Island of Misfit Toys while trimming the tree).
Did I miss any more?
I know that, while watching it, I was vaguely aware of the themes, but didn't put them together until later. I feel silly.