Things being on fire is a great shorthand way to indicate that things are going calamitously wrong, but there's still something you can do about it and, overall, in the big scheme of things, there are worse things that could be happening.
If something isn't on fire at least once in any adventure you run, seriously consider how adding fire might improve things.
Commentary by memnarch (who has not seen the movie)
Of course the Falcon is on fire. Because it wouldn't be as simple as Team Time Juice escaping from whatever was causing the hyperdrive jumps to fail. In the comic, trying to determine if it was a Jim-inflicted event would be an exercise in madness. Are we sure Rey managed to get all those brainwashing commands out?
Perhaps jumping through the space leech actually did some damage? That'd be a little surprising given the previous hyperjumps both in the movie so far and the previous movies, but oh well. It's probably something that's just glossed over in order to have the end result be what the writers want; in this case, the ship not being immediately able to fly away again. The Falcon probably won't take that long to fix given the many fixes it's already had though. Or maybe it will be a long time as a diversion to keep Rey from leaving on her own after talking to Kanata.
Snarky Chewbacca is still excellent as always.
Transcript
GM: The Falcon is on fire in several locations.
Rey: What happened?!
Poe: Technically, we made it back unscathed.
Rey: The fires kinda suggest otherwise.
Poe: Oh, now you’re taking the ship’s side in arguments?
Rey: Finn, what happened?
Finn: The First Order is experimenting with liquified space-time. R2’s got a sample.
Rey: Well, at least someone sensible was on board.
Chewbacca: {from background} I accept your compliments.
Poe: So... we have fire insurance, right?
Finn: How can you think of insurance now?
Poe: Just saying. This would be the perfect accident.
BB-8: “Accident”?
Poe: Who can say if it was an accident, or enemy action, or... you know, self-inflicted?
Rey: You... didn’t...?
Poe: Of course not! And that’s what I’ll tell any insurance assessor!