Schwartz's screaming "uncle!" while being essentially tortured is pretty disturbing.
Just before that freak gets the beatdown from Ralphie, he taunts the latter with faux-crying. The zoom-in on Scuts face while he does that and the shrill noise he makes is just....*shivers*. Gawd! That's one UGLY kid!
The scary department store Santa going into slow motion, with the music in the background slowing down to match.
Aided and abetted by the 1st Person POV fisheye camera shots as Ralphie goes up to see him. We see a distorted and fast view of a very bitter Santa (with lurid red nose) and two mean elves! HO... HO... HO.....