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.
"Funny Aneurysm" Moment: Marcia Wallace, who plays Edna Krabappel in the show, died in October 2013. This was during the 2013 Halloween Event, during which the characters can get possessed by ghosts, including Edna. It doesn't help that she doesn't speak at all in the game..
Heartwarming Moment: The loading screen for the Christmas 2013 update involves Homer walking with the gigantic finger as if walking with a good friend. This is opposed to the rest of the year, where most of the time the loading screen depicts Homer running from the finger in terror.
For Valentine's Day 2014, Homer and the giant finger are walking on a beach with hearts floating around them.
For the Thanksgiving 2014 update, you can let Hugo eat Thanksgiving dinner with the rest of the Simpsons.
Nightmare Fuel: During the 2012 Halloween update, when Springfielders are attacked by zombies, they would be covered in streaks of blood and then become zombified. Some of the zombified characters looked kind of unsettling.
The Scrappy: The elves from Christmas 2K14, for being annoying and the subject of an Anvilicious message about the treatment of immigrants. Though it looks like the creators foresaw this and had them be treated very poorly in the second half of the event.
Seasonal Rot: People didn't like the Clash of Clones campaign, which went on for too long, had some lackluster rewards, and forced you to build ugly castles that took up a lot of time and resources to make, and took up a lot of space.
The Woobie: Hugo. Not even his pigeon-rat likes to be seen with him.