Bokusatsu Tenshi Dokuro-chan Easter Egg - 4 anime references and 1 re-reference

In episode 6 when Dokuro and Sakura are walking alone in the forest and Dokuro is saying how she doesn't believe in ghosts and monsters, Sakura replies something along the lines of: "But you're an angel, and if you exist then all those other things must be real too! Like robot cats from the future, reindeer doctors, nurse witches and moving castles ...they must all be real!"

The "robot cat from the future" is a reference to Doraemon, a manga and anime from the 70's/80's (and if you keep an eye out there's a lot of Doraemon references in other episodes as well... I suppose most of today's manga artists grew up on it)

The "reindeer doctor" is a reference to Chopper from One Piece.

The "moving castle" is a reference to the movie "Howl's Moving Castle"

The "nurse witch" is a reference to "Nurse Witch Komugi" An anime parody in kind of the same style as Bokusatsu Tenshi Dokuro-chan, with a similar twisted sense of humor.

The makers of Nurse Witch Komugi picked up on the reference though: In the last few minutes of the very last Komugi episode they (briefly) show a figurine of Dokuro-chan on a guy's computer desk.

I guess it's their way of saying "yeah, we like your show too"