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.
Award Snub: The 2002 Cartoon Network special The 1st Ever 13th Annual Fancy Anvil Awards Show Program Special (Live in Stereo) featured What's Opera, Doc? as one of the nominees for the Best Cartoon award. Unfortunately, it lost to the Dexter's Laboratory episode "Mock 5".
And of course the short was not nominated for an Academy Award. (Warner Bros. instead nominated Tabasco Road and Birds Anonymous, the latter of which got the Oscar.)
Nightmare Fuel: For anyone who had the misfortune of seeing this when they were too young. You're expecting a normal, happy cartoon, and then Elmer Fudd SUMMONS A STORM THAT SEEMINGLY KILLS BUGS BUNNY!
The beginning of this cartoon seems like a Shout-Out to the Night on Bald Mountain sequence from Fantasia.
That terrifying brief moment after Elmer realizes his "twue love" is Bugs in disguise: Bugs runs away into the darkness of deformed canyon walls, the music turns ominous, and Fudd finally gets his helmet unstuck to scream "I'LL KILL THE WABBIT!" with a berserker rage that would scare the Devil.
Weird Al Effect: This short is arguably the source of many a modern person's knowledge of all things Wagner, to the point where some people don't even know the short was actually based on a real opera.