Yakko, Wakko and Dot return for all-new big laughs and the occasional epic takedown of authority figures in serious need of an ego check. Joining the Warners are Starbox & Cindy on their latest play date while Pinky and the Brain's ideas for world domination lead them to all new adventures.
A scene in s1e13 "Hindenburg Cola" has Wakko regrow his tail like a salamander. While the blood is green, it's still quite graphic and gross: the veiny flesh grows over the bone as the green "kid friendly" type of blood gushes out. S3e4 "Mad Mouse: Furry Road" has Pinky get a gross, gorey sunburn down to the bone with actual red blood.
The "targeted ads" in s2e10 include a tarantula whistle that apparently controls tarantulas. It doesn't do very well, and users get attacked. S3e4 "Uber Nachtmare" features Dot's pet tarantula Tobey Macguire. At one point Tobey crawls up Scratchensniff's shirt.
In s1e7 "France France Revolution" one crawls out of Marie Antoinette's fingernail in a very gross close up scene. S2e2's safety tips segment has a gag where Wakko sticks his hand in an ant farm while it is covered in syrup, leaving only bones. S2e12 "Narf Over Troubled Water" has a scorpion. S3e2 "Soda-pressed" also has some bugs in the musical number.
Played for laughs at the end of s1e13 "Rodent Trip". Pinky and the Brain presumably, in slapstick cartoon fashion, survived just fine. We do not see the impact.
All the animal related ones below, plus a rather bleak ending where everyone presumably dies from a meteorite (one that was rushed due to sudden cancelation).
This is a case where I really wish there was a "maybe" option when I'm otherwise fine without it, because s2e11's history song has Yakko say maybe half of the word "sh*tty", but he gets cut off.
S1e11 cold opens with a Poltergeist parody. The ghosts are the Warners and rather non threatening to the audience, yet do get a fright out of the family they are haunting.
An episode involves Pinky and The Brain getting a dragon actor to pretend to die in an effort to take over the kingdom, but his overacting proved that he was still alive and okay.
No incarceration, but the Warners are supposed to be locked up in the Water Tower. But they break loose and then vamoose and well... now you know the plot.
A bit has Wakko being used as a battering ram by Yakko and Dot to open the water tower, and he has chipped teeth for a moment before they go back to normal.
The hunter in s1e5 "Good Warner Hunting" successfully catches the Warners in a sack, and they don't get out until they are at his place. Once they're out, they easily win. S3e6 "The Island of Doctor Warneau" also has some restraint.
!!Spoilers!! S1e13 "Rodent Trip" reveals that the reason why The Brain wants to take over the world is as vengeance against the human scientists that, when he was a baby, put him through an experiment that involved him getting an electric shock every time he tried to get some cheese. Notable in that it is the one scene in the show that is undeniably NOT played for laughs.
Wakko graphically grows his tail back in s1e13 "Hindenburg Cola". S2e9 has a segment that parodies prescription drug ads and shows some body horror side effects. S3e6 cold open has body horror alien Warners as a parody of the movie Alien, and has some body horror-y (good guy) mutant Warners in "The Island of Doctor Warneau".
In the "Short Short" in S2E1, there is a scene where one of Wakko's eyes pops out and rolls away and he puts it back in. It's cartoon logic. No blood, gore, or obvious pain.
There is an episode directly parodying the film IT, wherein Yakko, Wakko and Dot deal with a version of Pennywise, but he proves ineffective, even though Wakko is normally afraid of clowns.
S1e11 has a cold open parodying Poltergeist and includes scenes of a young girl getting creepily attached to a static television. The ghosts themselves are the Warners and not very scary to the viewer. S2e2 "Please Submit" has Wakko get possessed by spam emails.
Aside from the scenes in The Cutening (S1E6) and Backwards Pinky (S2E1) there's also a vomit scene in Suspended Animation part 2 (S1E1), a resurrected frankenstein's monster throws up money. It's not exactly vomit and doesn't have sound, but you can see the liquid-like money coming out from his mouth for various seconds and it's very uncomfortable (min 22)
If burps go under this category, that is one of Wakko's trademarks. The beginning of season 3 has a lot of spittakes. A dog in one of the season 3 Starbox and Cindy segments drools a lot in one scene.
Briefly, in the Catch Up song from the first episode ("has it all gone mad since we went away?") S3e4 "Uber Nachtmare" ends with Scratchensniff straightjacketed and thrown into a van with padded walls.
People with claustrophobia should get a heads up on a scene in s1e5 "No Brainer", where The Brain defeats an NSA security man by learning of his claustrophobia and locks him in an elevator. The camera angles make it look like the walls are closing in on him and there is very tense music by this shows standards as well. He never gets out. I could see it being quite upsetting.
Though it is worth noting that they made the interesting choice of having Doctor Scratchansniff, a character with a big nose, play Fagin in the Oliver Twist parody "Wakkiver Twist" (s2e8). As one of the Warner's typical adversaries, and with Rob Paulsen's lovely singing voice even as Scratchy on full display, I'll give benefit of the doubt and assume this was unintentional.
The show is completely safe in this regard. The fanbase of the show, on the other hand... trigger or not you might want to stay away from certain people.
Through no fault of the creator's own as they had to suddenly come up with an ending after the series was abruptly canned, the show ends with a meteorite killing everyone, in stark contrast to an optimistic song about humanity being awesome earlier in the episode.