In "Dueling Buttons", Corey became obsessed with defeating Trina in a video game after she won. According to Word of God, Corey has A.D.D. and O.C.D., so of course he would act this way after a loss!
In the second half of the series, the Running Gag of Corey and the Kujira twins misgendering Laney is largely dropped. Word of God says the guys know Laney's a girl and treat her as a boy so she feels like she fits in, but Laney's reactions indicate she doesn't like being called a boy. That must mean that at some point, the guys must have learned Laney didn't actually feel comfortable with what they were doing and decided to knock it off! This might also explain Corey's development of his feelings for Laney later on, since he no longer has to treat her like a guy. It also doubles as a Heartwarming Moment if you think about it.
In "Girl Fest" Laney's criticisms of Candy Jams as a boy-crazy girly girl unable to come up with her own songs sound extremely hypocritical at first (since Laney is a Tomboy with a Girly Streak with a major crush on the lyrics-challenged Corey), but the more you think about it, the more you realize they aren't. First, Candy Jams was extremely superficial in her crush on Nick Mallory, worshipping the very ground he walks on and still obsessing over him after their relationship ended whereas Laney is not afraid of criticizing Corey despite her crush on him. Second, while Laney does have a girly streak, Candy Jams cares more about fashion and looking good (and making money of promoting such) than her own music while Laney's true passion always remains with the band and its music. Finally, while Corey always needs Trina's diary to make songs, the lyrics are never directly stolen but created on the fly as he sings of whatever Trina has written about (In "Space Jammin'", The Orb Experience literally did just read Trina's diary out loud for a song, and the result was treated as an Epic Fail). In contrast, Candy Jams just sings whatever her agent writes for her with no understanding what she's even singing about. In a nutshell, Laney wasn't directly reflecting her own faults but pointing out why she and Grojband are still better than Candy Jams despite sharing similar flaws.
The Bonkerton comet. When it comes around, literally anything can happen, and there's no controlling it.
At the end of "Hologroj", Trina snaps and and has an existential crisis, believing that nothing is real. This becomes pretty horrifying when we never actually see her recover - it's only assumed.
In "Grin Reaper", Torbo is revealed to be sucking happiness out of people, leaving them as piles of ashes. We see he wiped out three other towns (North Mountainfield, South Mountainfield, and Extra-South Mountainfield) before coming to Peaceville. In the end, we see a bunch of Peacevillians brought back to life by Grojband's song, but as far as we know, the citizens of the other towns affected are still dead.