A one armed man is used as a mysterious and ominous figure, and a main chararacter played by David lynch pretends to be deaf for jokes. Both are in good faith and not too offensive, but if you’re having a rough day it’s worth noting!
Just wanted to add that in episode 18 there may be an on screen rape as well. It’s ambiguous as to what’s going on and it is supernatural in nature (like a dream or hallucination) but at least in my interpretation it is a slow and uncomfortable rape scene
In episode 3 when the doppelgangers are being sucked back into the black lodge they both vomit very graphically horrible material, it goes on for quite awhile.
A trans woman character is played by a cis man. It’s this way in the original series and they wanted to bring the character back, but it’s still worth noting. The character is also deadnamed briefly in her only scene. Overall the scene is really sweet and clearly has good intentions, but it’s still obviously written by an old cis guy. It’s a nice surprise if you’re a fan of the original show, but it’s worth being aware of if you’re not feeling up to some messy handling of trans representation