Game Masters should do their best to encourage roleplaying and group cooperation to overcome obstacles, rather than appealing to rulebooks and trying to numerically optimise game mechanics.
One method to do this is to make the challenges they face always just a little more than they can manage with their individual gear and skills. The difference needs to be made up with teamwork and creative thinking. You don't really need to plan out how they'll overcome the problems - their own ingenuity will take care of that, so long as you are not stingy in giving them a fighting chance.
Commentary by memnarch (who has not seen the movie)
It's why you wouldn't want to leave your staff behind Pete. And also why arguing with the GM won't end up well if the GM insists on something. They don't aim to actually be deadly with adjustments though, so there's probably an easy way out of this current predicament. Or at least, something the GM will essentially say "That works!" to and the game can continue on. Thinking about it a bit, I actually can't think of any GM-run tabletop games that don't have some version of Rule Zero explicitly or implicitly stated.
And this is a great example of protagonist importance. Every other rathtar victim was grabbed and eaten much faster than Finn. There's practically nothing for Finn to grab onto in the hallway to slow down or stop the dragging. And Rey is dodging all of the tentacles being waved in her direction. But they're not dead yet! Pete's comment here makes me think we'll either see the door slam that seemed possible before or maybe we'll have another instance of someone getting spaced. Getting spaced would be pretty neat, but then there's the problem of not spacing Finn at the same time. It would be more survivable than getting eaten though.
Commentary by Keybounce (who has not seen the movie)
So the Rathtar has more than one tentacle. And the other ones can keep Rey away from the one with dinner.
For some reason, I'm thinking that the next scene is going to be some sort of acrobatic leap or something, some sort of somersault to get the high ground, or some sort of silliness. With just normal dice.
Note that Pete is trying to quote the rules. Clearly, if this was a game where following the rules was the issue, lawful neutral Pete would be in great shape. Suddenly, I find myself thinking of Pete as an old-school fey.
Rey: See, this is why I wouldn’t leave my staff on the Falcon!
GM: You had to drop it to hide under the floor, and a few seconds later you were running outside.
Rey: With a 3-metre reach weapon the rulebook says—
GM: The rathtar waves its 5-metre tentacles at you menacingly.
Rey: All right. I tried my best, Annie.
GM: Books! And cleverness! There are more important things - friendship and bravery and—
Finn: Oh Rey, be careful!
Rey: I have an idea! Just hold tight!
Finn: The rathtar’s doing that for me!