Harmy said:

Well, I guess it's true that the whole concept of a space slug like that is so implausible, that any discussion of how certain scientific principles apply to it is probably quite pointless ;-)

Though implausible, it's relatively too much. Most movies are implausible on some level. But movies tend to set rules for themselves on the level of suspension of disbelief. I can buy into the concept of a giant space slug in the Star Wars universe. I can even rationalize the gravity issue to myself within SW context (perhaps the cave curved so that outside the Falcon we still face down, and few movies accurately represent low gravity). However, I can't buy into no pressurized suits. That may be the one big issue that has always bothered me a bit about this movie.