Freud Was Right: As mentioned on the Does This Remind You of Anything? trope of the main page, Key Princesses act rather . . . weird when having keys plunged into their chests. Shown by Arisu in the manga, it apparently works if you insert it in the back too.
God-Mode Sue & Relationship Sue: Invoked by Arisu in the manga. Because she's Aruto's creation and is essentially empty, she can change to any power whenever Aruto writes into her story. She also appears as Aruto's perfect girlfriend because he's squicked at the idea of being in love with his sister.
Shocking Swerve: In the anime, Liddell kills Takion out of jealousy and she wants the power of the Never-Ending Alice for herself.
They Wasted a Perfectly Good Plot: Arguably. Despite ostensibly being about a There Can Only Be One scenario, the anime and manga focus mostly on the characters, only actually showing a few of the fights (most of which are fairly lazily done). You can actually find artwork of the other Seekers of Alice who never made a full appearance around, and see profiles of them on the show's site. Sort of a shame, since a lot of them seemed like they'd make fairly interesting battles.