can you leave Ultemicias "time" after you enter?

[...]

I wanna leave to get my best weapons and the rest of the GFs and level some more but i dont know how to leave Ultemicias "time"

[Mo-Nercy]

You sure can leave. Go back down the chain to one of the doors that float in mid air. Jump through that. Ta-dah...

However!!!

All cities will be closed off to you. There is no where for you to go and nothing for you to do (except fight on the world map)...

Except!!!

One of the doors will take you to a place where you're in a forest, by a beach. Wander around this forest to find a chocobo forest. Take the Chocobo here and manuever through the shallow waters to the Kashkabald Desert where you'll find the Ragnarok. However, it will be empty...

Unless!!!

You have beaten the CC Group in Balamb Garden earlier. In which case, the whole CC Group will be there. Including Joker who does sell items but I'm not sure if he makes weapons...

But!!!

If you have Tonberry. No problem. He can make weapons and sell items to you no matter where you are.

[Zante]

And you also can go to the cetra ruins to get tonbery and odin, get the solomon ring from tears point and get eden from the deep sea research center.

[Xzirox]

Yupp, AND theres a fourth "floating" door next to Ragnarok that wll bring you right back to Ultimecias Castle again!

[Loony BoB]

It sure does suck that you can't go back into the towns again. I hated that so much. It was the biggest letdown in the game, at least for me.

[BG-57]

I found it best two create two save files: one right before entering Lunatic Pandora on disc 3 and one in the Castle on disc 4. There's nothing in the Castle that you can't pick up earlier.