More than a year after Disney's Frozen blew into theaters, the highest-grossing animated film of all time still casts an icy shadow across the cultural landscape -- so much so that The Simpsons makes an "Obligatory Frozen Reference" in the couch gag for Sunday's Christmas episode.

It's fun, but the rest of the opening is better, as the producers go all out, transforming Springfield into a winter wonderland populated by elven versions of the characters, with nods to A Charlie Brown Christmas, Seinfeld, Rudolph the Red-Nosed Reindeer and The Lion, the Witch & the Wardrobe.

The Simpsons airs Sunday at 8 p.m. ET/PT on Fox.