Deliberate mistake: In this episode, Ray tells Amy's mother that Debra no longer reads his column, although she did when they were dating "and she was wooing me." But in an earlier episode, Ray proposed to Debra in his very first column - so when they were dating, he didn't have a column.
Deliberate mistake: Season 2, episode 6 "Identity Crisis": When Bizarro starts decaying into the parody form of Superman, his costume goes with it; the blue fades, and even the 'S' insignia changes. Strange that superhero garments change right alongside their wearers when they suffer from an unstable genetic effect. Were the clothes cloned right onto his body, instead of sewn?
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.
Deliberate mistake: When She-Hulk walks up to the bar, she asks the bartender for a cream soda with a mint twist, which the bartender gives her immediately, with no time to pour the drink.
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.