Ensemble Dark Horse: Bunny. Despite only appearing this episode, she became popular amongst various fandoms, to the point some viewers have made various fan arts of what Bunny would've looked like if she were created properly.
Hilarious in Hindsight: The girls creating a fourth girl to help with their crime fighting becomes this in the reboot when we are introduced to an actual fourth Powerpuff Girl (and the original), Blisstina.
Cover Up:
Alternative Character Interpretation: Were Blossom and Bubbles really upset at Buttercup for relying on a blanket to feel confident when fighting or were they just concerned that her reliance on the blanket was starting to negatively affect her crimefighting duties?
Never Live It Down: Many fans will not let Blossom and Bubbles' behavior towards Buttercup in "Cover Up" slide (especially Bubbles, considering her Octi doll has made her behavior seem hypocritical), despite them being genuinely nice people for the most part.
They Wasted a Perfectly Good Plot: For an episode about security objects, it's quite bizarre that Octi isn't even mentioned oncenote unless you count Octi's brief cameo in the episode, as Bubbles' Octi doll could've been used as a good comparison to Buttercup's blanket. This also could've been a good opportunity for the Professor to console Buttercup, like he's done for Blossom and Bubbles in their own episodes, as it's never happened in the original series.