Facts:
When you enter world 57, you spawn on Tutorial Island (as a fresh spawn) momentarily, and then you are translated across to the Clan Wars location.
When you leave this world, you go back to your original account as normal.
The first step would be to escape from Clan Wars, but the road to leave is blocked by rocks, the Ardougne cape's teleport, default home teleports for all spellbooks and the minigame teleports are all blocked. There are no law runes, nor any means of acquiring them, so there's no way to test the other spells (perhaps this is an oversight on Jagex's part--seeing as they do not give you laws, they may have not blocked the spell). I doubt there's any way to get your hands on a ring of life, or a diamond ring, because if you could, you might be able to forcibly teleport yourself out of Clan Wars via entering the arena and getting below 10% hp.
There's one way to acquire items not provided by default: hunter kits. At best, laying a trap will move your player one square. Though I doubt you could use this as an exploit, and it's not like you can try it out during the battles since...y'know, fighting and all.
Jagex has not added an amulet of glory to the chest, and I think this is partly due to the fact that the fury is better and because there's a 'recharge dragonstone' spell in the lunar spellbook. If you can somehow get your hands on an dragonstone item, that might be your ticket out of Clan Wars.
The only other option I can think of is the ability to die outside of Clan Wars, but there doesn't seem to be any means of achieving this that I know of.
Once you get outside of Clan Wars, then what? There'd need to be some kind of place where you can 'deposit' items briefly, that will then pass on through to the main game. It's possible Jagex has a major oversight issue here also. There might be some kind of quest feature that requires you to briefly hand over an item. Perhaps you could build your POH and use the costume room. Who knows.
I'd be really interested to find a flaw in this. I would love to crash the RuneScape economy, lol.
Back onto the hunter kits.
Baby implings reward ball of wool and chisel.
Earth implings reward uncut emerald, cur emerald and a cut ruby. Cut ruby can be used in part to make a digsite pendant.
Essence implings reward law runes.
Exlectic implings reward gold ore, five noted gold bars and a cut diamond.
Magpie implings reward a ring of life and a cut dimaond.
Dragon implings reward a dragonstone amulet and a amulet of glory.
If by any chance you see one of these imps crossing Clan Wars, get yourself a hunter kit and go catch it!