The animation throughout the first 10 episodes seemed pretty consistent to me.
However, episode 11's style had nothing to do with the first 10 episodes (though it was probably consistent throughout the episode):
Since this show is filled with references to other anime, it occurred to me that the change in style could be a reference in itself. If so, what was it a reference to?
If not, why the sudden change in style? Was it due to budget or something similar, or did they just decide to go on a different direction for some random reason?