Sometimes things can be noticed through unconventional means. The GM usually describes things of importance in a game as seen, or perhaps heard. But we have plenty of other ways of noticing things. Sensing vibrations and low rumbling indicates something big and heavy moving nearby, which can be significant in many ways. In a technological setting it could be a large vehicle. While in a low-tech setting it probably indicates something potentially more dangerous, such as a large monster, a rampaging horde, or magic at work.
Consider a group of fantasy heroes relaxing in a local tavern. When suddenly the room starts shaking and a thunderous roar is heard from outside. You know something epic is about to go down!
Commentary by memnarch (who has not seen the movie)
Alright. MST3K mantra, engage!
This is hitting lots of the parts of a casino I'd expect to see in a movie. The drinks must be pretty cheap as well, or free, if the patrons don't seem to care about the spillage. All that's left is an oversized fish tank or an expansive restaurant of some kind. And of course, the vaults. It'd be really strange to have a casino show up without seeing the vaults or a giant vault door at least.
So what are we going to have next? Random betting on the horse things? Dice, cards, and
one-arm bandits slot machines aren't as exciting to watch as a race. BB-8 getting chased by the little alien, still attempting to stuff the droid full of coinage? That'd be an amusing way for them to get free money to start with, so that seems likely. Time to move to a heist sequence? Perhaps we need to see how bets are being placed first. And while it'd make a lot of sense for a heist sequence, I doubt that we'd get a bunch of flashbacks/flashforwards to different planning or action parts; there's too many other plot threads happening elsewhere in the Galaxy.
Funny sidenote; on my first look through, I mostly just saw the images, so I'd thought there was a glowing fish thing levitating in the third panel until I actually read what was happening.
GM: Finn doesn’t see any overt security. There may be plain clothes guards or hidden cameras though.
Finn: How’s the schmoozing going?
Rose: I’ve traded meaningful glances with a few patrons, encapsulating our mutual derision of the hoi polloi.
GM: Suddenly the casino starts shaking to the sound of heavy rumbling outside.
[SFX]: rumble... rumble...
GM: Everyone else takes it in stride as drinks vibrate and splash all over the bar.
Finn: Is this planet seismically active?
Rose: No. It’s coming from outside. There’s a balcony over there.
GM: You see it’s the thundering of hooves as jockeys race on fathiers around a track.
[SFX]: rumble... rumble... rumble...
Finn: Animal racing? Can this place get any more depraved?
Rose: We can only hope so!