These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
YMMV: American History X
Crosses the Line Twice: Seth's white supremacist rendition of The Battle Hymn of the Republic. The lyrics are hateful and racist, but Seth's exuberance while singing makes it uncomfortably amusing.
Even worse, that's an actual song by Johnny Rebel.
Crowning Moment of Funny: in Derek's prison flashbacks where we expect to see him come up against the black gangs for his actions outside - 'Don't fuck with me, 'aight? 'Cause I'm the most dangerous man in this prison. You know why? 'Cause I control the underwear.'
Fridge Brilliance: This is mostly in the script and cut from the movie. Danny is an impressionable kid who follows Derek's lead. Henry, the black kid who Danny has a conflict with at school, was pressured into it by his big brother (who he seems to idolize). He's in the exact same position as Danny.
Misaimed Fandom: In spite of the film's anti-racist message, it still has a large number of Neo-Nazi fans due to the fact that Derek is strong, charismatic, and a natural leader. See Do Not Do This Cool Thing.
Moral Event Horizon: Derek shooting at the armed assailants intruding on his home is defensible as defense of home, but when he kills one of them after he seriously wounded him is sailing over the line.
Though not directly seen, the infamous curb stomp will haunt your nightmares long after the credits.
As will the expression on Derek's face as he's being arrested, smiling as if he had done nothing wrong.
A gang of jack-booted, stocking-capped thugs storm your home and trash it while telling you to "go home". They drag your cashier onto the counter and drown her with milk until she's white. If you don't want to become white, they have baseball bats to convince you to try.
Some Anvils Need to Be Dropped: There is still a shockingly high number of Neo-Nazis both in California and Tony Kaye's native England. There's no other way to say it, either; racism is a pointlessly destructive thing.
As the movie goes, it becomes clear that the neo-nazis aren't the only racist people around but the black gangbangers are just as racist toward white people as the neo-nazis are racist toward black people. The point is that whites aren't the only people who are capable of racism but also the very same people they hate are also capable of that, and sometimes that is what drives normal white people toward neo-nazism. It's an anvil that seriously needed to be dropped since every time another movie comes with An Aesop against racism, its becomes pretty broken when they almost always portray western or European people as the violent and greedy scum of the Earth while the Africans, the Indians, the Asians, etc are portrayed as the innocent, poor, peaceful, spiritual superior human beings.
Or you could argue both of the above are wrong, and the real message is two wrongs don't make a right, to both blacks and Neo-Nazis. The racism that black people feel towards whites now does not make what whites did to blacks acceptable, and neither does the fact that whites were racists before make it acceptable for blacks to be racist now. That goes to the argument about Europeans and the West, as well: earlier works of fiction portrayed the Europeans as the heroes of the human race who needed to teach childlike natives how to be civilized. Now the Europeans are portrayed as evil. Neither portrayal is correct. Also, the fact that Europeans are portrayed badly now does not justify the way natives used to be portrayed. And vice versa, the fact that whites behave like assholes does not give non-whites license to do the same thing. The whole point of the movie is that if either side keeps race relations hostile, it's wrong no matter which side is doing it.
Squick: Derek curb-stomping the black guy to death.
Tear Jerker: The ending, so very much. And the flashback.