nathan says it as a joke in a flashback scene to the bowling alley employee. and he says it again in the next season where he's gonna kill himself on live television.
Alisha forces multiple people to have sex with her using her powers. Personally I see that as sexual assault, but it all depends on how you perceive it.
There's a scene in the third episode where Alisha almost gets r*ped by two men thanks to her powers, but she gets away
The character is immortal but no one knows that yet so they get buried. There is no struggling or panic and you don't actually see them until they're dug up agaib
Simon gets visibly nauseous after he turns invisible in the third episode of the first season, and Nathan gags a few times in the second, but so far nothing ""substantial"" is shown on screen. Nathan does a lot of retching in the third episode, too, and he's heard spitting off screen. It's not obvious whether or not he actually vomits. Kelly throws up in episode 4, you'll know its coming because Curtis approached past Kelly on the stairs
S2 ep6 one of the characters shoots themselves in the head. They are immortal and so know they will come back to life, its to demonstrate their power now they're famous.
The first episode has a black Villain Of The Week, though the main cast also has a black guy who is the last of the original cast to die (aside from one character who does not die during the show).