Careful parties should always set up rendezvous points in case something goes disastrously wrong and they get separated. (What are the chances of that?)

If you're about the enter the Dungeon of Doom, arrange for people to meet back outside at the wilderness camp a half mile away if anyone gets separated. Then when it inevitably happens, you have at least some chance of regrouping even if it becomes impossible to track down where the separated party members have been imprisoned or teleported to.

This simple expedient could have saved thousands of adventurers who stepped through that mouth thing in the Tomb of Horrors. Well, it would have if [spoiler: highlight to read] the chosen rendezvous point was OBLIVION.

Transcript

R2-D2: Feeling better?
Luke: Much. Thank you.
R2-D2: I brought our X-wing out here. It was getting a bit hot in the hangar.
Rebel Trooper: {faintly, in background} Yah, the Clabburn Range got completely smoked...
Leia: {over radio} Luke, the base is lost. Get out of there!
Wedge: Yeah, c'mon good buddy. See you at the rendezvous point.
Luke: Right. Remember, it's rendezvous point... Zeta.
Wedge: Gotcha, buddy.
GM: Okay, that's the end of the battle. Good time to break for tonight.
GM: Play again Friday?
Luke: Yeah, I can't wait. Did everyone get out of the base?
GM: General Rieekan stayed behind.
R2-D2: An unqualified success!