Esther Rosenthal is introduced in this episode and with her comes the main plot of the anime. If you've watched Index, you'll already be familiar with the dark side of Academy City and its inhabitants. This episode also features some of those denizens. If you're observant enough, you might notice something familiar about the large spider-like robot they're using. The animation is surprisingly good, it seems that they have used the same animation techniques they employed in Heavy Object for the robot and improved upon them.

P.S. I'm really holding myself down in not spilling too much information about any small foreshadowing in this episode since even with a small hint would be a spoiler.