Well, here goes me blowing my security clearance! I'll provide 3 that are "common" hopefully to sate your interest and not give away all the secrets until you are at the cult's compo..... social group retreat center and prison.
Now!!!! For the love of Pete do not do anything that would make the devs put down their sodas and go "Well, I guess I have to drop working on this awesome new power adjustment for force field sets (ahem) and instead fix this boundary stuff because xXxNinjaKilla420xXx was a jerk and ruined it for everybody."
RWZ - go to the point where you are between the zone's giant robots outside the base and the teleportation circle. Right in that archway area. Push your butt against the wall. Log out and then back in and of course, fly ready.
Kallisti Wharf: Fly up and over the war walls (ta da!).
Pocket D in the tiki room. Right next to the door look up - there is a triangle space between the rocks you can teleport through. Once you are out you have to navigate a maze of walls to get out proper and be able to see the blue box of time traveling physicians and fly to the mothership (which is full of Dole Whip).
A VERY interesting thing I discovered is if you ask Null the Gull to send you to a different place, like Spooky Atlas - then log out, in the character select screen your character is listed in Nova Praetoria. Now, Spooky Atlas and the like are "static" so no functional building or mission doors, train stops, portals, or NPCs. The zone is functional in every other way. If there was an escape from there (or perhaps an Atlas escape that could be applied there) you might see a lot of interesting junk drawer items around Nova.
I've spend some time flying away from the central zones and never was able to find a terminal wall border or touched the moon. YMMV.
Better? Curious? Secretly a dev looking for things to patch because you are out of soda?