*Arthur's Big Hit: D.W. crosses the line by trespassing in Arthur's room, steals his model airplane that he worked hard on, and just throws it out the window thinking it can fly. The plane breaks. Arthur finally gives D.W. some discipline and she ends up crying. Their parents ground Arthur from watching t.v. All of Arthur's friends agree that Arthur was wrong for hitting D.W. and take her side. Binky hits Arthur and his parents don't care at all other than giving him an icepack and Binky doesn't get punished for it.
*Nerves of Steal: Buster steals a toy and gets himself and Arthur in trouble. 'Nuff said.
Veronica Mars - season 3 as a whole was just a disaster. The creepy overarching mystery format was abandoned in favor of two shorter arcs with few suspects and little audience emotional investment; the earth-shaking season 2 finale was almost entirely ignored in favor of stand-alone stories that were supposed to bring in a new audience but instead just cost it the audience it had; the ridiculous amounts of misery the characters were put through just became depressing; after season 3 it got cancelled, so the whole "bringing in a new audience" thing was pointless anyway, leaving seasons 1 and 2 to become cult classics but ensuring that there would never be a season 4.
Phineas and Ferb: Across The Second Dimension
While Phineas' reaction to Perry being a secret agent was fairly humorous, out-of-character, and unexpected, he kind of overreacted, up to the point where he sounded like Candace, IMO saying that Perry did nothing to stop him and Ferb from opening the second dimension's portal when that's not true.