The Turtle Bath and the Grill Pelican are based on oriental deities which guarded the four hemispheres - North: Genbu (black tortoise), South: Suzaku (red bird/peasant/peacock/phoenix), East: Seiryu (blue dragon), and West: Byakko (white tiger). Hence the location of the establishments corresponds to their deity counterparts.
In episode 3, starting with the "launch sequence" and continuing on through much of the robot combat, the background music is the "angel battle" music from Neon Genesis Evangelion (1995) (also produced by Gainax).