Actor Allusion: Seraphim'scat-ears experience. Amusingly enough, earlier in that same episode, Maelstrom pulls off the "Moe Moe~ KYUN!" stance while her classmates are trying to help her get Ayumu to reciprocate her love for him.
The Ninja Maid scene that serves as the season's climax, though, does play this straight, minus the "Moe Moe~~ KYUN!" bit.
The cat-ears return in Of The Dead Episode 7.
Fan Nickname: Sometimes the series is jokingly nicknamed "Korean Zombie Desk Car", as a mispronunciation of the Japanese title.
Follow the Leader: To Princess Resurrection, indeed there are many similarities (male leads who're undead servants, female monsters join the household, group battling other monsters, chainsaw motif etc) but both series are original in their own right.
Genius Bonus: Chopin's "Tristesse" plays in the bowling alley scene in Episode 3.
Too Soon: The last three episodes were delayed a week due to the Sendai earthquake. Apparently, the broadcaster decided that showing an anime with "violent content" so soon after the 9.0 earthquake would offend sensitive people.