In episode 5 a war starts between two kingdoms, one with anthropomorphic dogs and another with monkeys. Several characters from both sides are presumably killed.
[Spoilers]
At the end, the two kingdoms sink and almost all residents drown apart from a couple of survivors.
In episode 9, Paula, who is a minor, misinterprets a comment and imagines herself wearing a bunny suit, the sexual kind. The other characters quickly correct her, but the image of her wearing it is shown.
In PaRappa’s nightmare, first episode. Two characters’ faces melt and turn into liquid.
In the outro, PaRappa walks around giant versions of some characters’ faces, sometimes getting inside and outside orifices. Even if not that graphic, maybe it could come as a bit off-putting to some.
Episode 12. A ghost/arachnid character opens their skin and makes their insides “grow” into a flesh flower resembling Sunny.
For a split second, a character shows a nosebleed during episode 10. It’s almost unnoticeable.
In episode 12 the characters think that a ketchup stain is blood and PaRappa touches it. It’s not the same but could feel uneasy to those people scared/disgusted by seeing blood.
In episode 5. The king treats his daughter poorly, insults her and forces her to marry. He starts a war with another kingdom when she refuses to marry someone she doesn’t love, putting her and everyone in his own kingdom in danger.
For some reason, in episode 11, during Matt’s auto-motivation talk, the camera gets close to his teeth to show an imaginary mini Matt in one of them, like if he was a cavity. Another mini Matt then comes from below that same tooth and takes it out. All of this doesn’t actually happen, and there’s no blood.
Gaster’s and Groober’s teeth in episode 18. They have some missing after the crash.
Not slurs, but in episode 9 a character stops Gaster and Groober from entering a party together because “Same-sex couples are not allowed. It has to be a male/female couple.”
It seems like in episode 10 there were some gay innuendos/jokes played for laughs as well, nothing really harmful in this one.
In episode 3, PaRappa begins to wonder who he will get married to in the future. In one of his visions, the bride turns around to reveal PJ in a wedding dress. PaRappa seems horrified at this thought before he fully wakes up from the daydream.
Several times in the anime Gaster and Groober dress up as women in different scenarios as well.
In episode 17, PaRappa, Matt and PJ are forced to wear wedding dresses and act like mannequins. They’re not happy with this.
In episode 13 Paula seems to get a crush on Master Onion, but it’s a bit ambiguous if what she feels towards him is actually that or just a lot of admiration or an opportunity to use him in her advantage at the end.
Even if it wasn’t actually a crush, it is indeed presented in that way on purpose at first to make the audience think that what Paula is feeling is romantic attraction. Paula is a minor and Master Onion is an adult.
During episode 5 PaRappa is almost eaten by an alligator before he is saved. Some animals are eaten during this episode as well, included that same crocodile.
In episode 7. A character wets the bed (seen) after a dream involving firefighters, and then wets his pants every time he sees a firefighter (not seen, just mentioned).
In episode 15 PaRappa holds it in and then mentions that a little came out.
PaRappa tends to daydream and disconnect from reality quite a bit. The other characters need to grab him and run away with him in their arms during dangerous situations when that happens because he doesn’t react at all.
Cars and other vehicles like vans and tractors crashing are prominent in this anime, but no one dies except in episode 18. The episodes containing this kind of content are number 6, 11, 15, 17 (ships) and 18.
One of the stronger ones and that should be mentioned is in episode 11. A bus full of people crashes and falls on a train track and it’s run over by the train, which also gets heavily damaged. The visual and audio here is actually pretty shocking and horrifying for a kids show. It looks more detailed and realistic than the usual style of the anime. This scene got semi popular because of how bizarre it is.
Another that should be mentioned is one of the many in episode 18. A tractor hits a car and makes it roll several times before this same tractor crashes against a shop. The visual and audio here are pretty impactful.
[Spoilers]
The tractor then begins to move again and they crash into several and important buildings. Almost all the town is run over and destroyed. They finally crash into a sentient tree and stop, but this sentient tree dies.
An helicopter does at the end of episode 7, but everyone jumps out into the water in time.
In episode 8 Sunny imagines a rocket exploding with PaRappa, Matt and PJ inside. The real rocket then crashes without anyone inside at the end of the episode.
In episode 10 an airship explodes but no one gets hurt.
An ovni during a daydream in episode 13. It’s not real but the people inside get hurt and maybe even killed. One of them were Gaster and Groober in alien costumes.
In several episodes there can be seen hidden strange characters staring at the protagonists in some frames. These might be just Easter Eggs but can be pretty creepy sometimes, since they don’t move at all, some are in places they shouldn’t be or during private conversations, and some stare at the camera as well.
[Spoilers]
At the end, the two kingdoms sink and almost all residents drown apart from a couple of survivors.