Deliberate mistake: In Episode 7, "Bad Moon Rising": When Cash meets Sasha at The Haven, she mentions "Eddie and his bodyguards being blown away". But Eddie was not "blown away", he was neatly decapitated, and in addition, none of his bodyguards were killed. Julian specifically said that he would let them live to elect a new leader. Sasha was present, and would know this.
The High Life / Best Friends - S2-E10
Deliberate mistake: In "The High Life", there is a scene where Stinky submerges his head in a tank of water. He delivers the line, "Gee willickers, it's still ticking", and everyone somehow understands what he is saying with his head underwater.
Suggested correction: Nobody responds to what Stinky says, so there's no reason to assume that everyone understood him.