It gets to a certain point where you stop worrying about people being traitors and spies, because pretty much everyone is, and it all comes out in the wash. You could run a game around this principle, where everyone is keeping secrets from everyone else, and nobody really has any idea whose side anyone is on.
Bonus points if none of the players even know whose side their own character is on.
Commentary by memnarch (who has not seen the movie)
Finn is definitely a bad actor here, in both senses. I can think of a few things that Annie would have Finn say if he was a better actor. Like rather than saying "you could have learnt that from anyone", something like "I don't even know about any maps to find Luke" would be much better. And a technically true statement that still sounds false as well! I don't think the GM has actually confirmed Luke is still on Achoo, even though everyone else appears to be assuming so. There'd have to be something of importance as well for him to guard to make it worth sticking around instead of returning with Lor San and none of the players have brought up that possibility yet, though I hope resolving that side of the plot is left for another movie.
I think Phasma knows, but understanding her description of the location is going to require over an hour to understand if they want to find that out from her. Probably a lot longer, if grand operas tend towards the longer side of operas. And that Finn and crew would actually be better off going to talk with General Hux instead. It took me a bit to understand this metaphor, so I bet the GM either spells this out or we're going to end up with that saved time disappearing real quick.
Finn: Of course she’s going to say I’m a spy! She’s trying to sow discord.
General Phasma: Your report about the map to Luke Amidala was most useful.
Finn: You could have learnt that from anyone!
General Phasma: And we picked up Rey Solo thanks to you.
Zeppo: You are a spy?
Finn: I told her I wanted to be a spy, because they wouldn’t let me find out who killed my buddy Gil. Then they told everyone we were traitors!
General Phasma: To maintain you cover. Though to be fair, it sounds like you were.
Finn: I’m on your side! You gotta believe me!
Zeppo: Hey, I used to be a traitor too. It’s all good.
Finn: So where’s Rey?
General Phasma: General Hux has the spreadsheet mind for such mundane data. Mine is the grand opera to his schoolboy book report!
Finn: So you don’t know?
General Phasma: Must my metaphors fall on salted soil?