Most of episode 9 is filler material, except for the bit with the flying fish and mushrooms (not pictured). Even so, the part where Makarov rescues everyone sort of works in the show because this is the first time we’ve actually seen him do anything, and it shows that he’s the guildmaster for a reason. In an RPG though, having an NPC resolve everything like this isn’t ideal. The GM made a mistake in the way he set up this encounter and resolved it, but he made the right call by dropping this whole plot thread and moving to something else.
Makarov: I knew I could count on you guys.
Natsu: In we go!
Lucy: Wait! We don't know anything about them!
Erza: This is really fishy, but Natsu is right. Fight now, ask questions later.
Natsu: Huh? What did you say, Lucy?
Natsu: These guys are a total pushover!
Gray: They're way easier than that Lullaby thing.
Erza: And that's that.
Lucy: I'm getting a bad feeling about this...
Erza: They didn't put up a fight at all. What do you suppose it means?
Gray: Maybe they're actually people who were turned into monsters.
Makarov: What? That's ridiculous! This was just a trap to lure us in.
GM: A huge magic circle opens beneath you.
GM: You are now falling into it.
Lucy: Um, someone do something?
Erza: Right. The thing is, I'm all out of magic.
Gray: Me too.
Natsu: We spent it all fighting the monsters.
GM: Are you serious?
Erza: Afraid so. I guess Happy will live.
Makarov: Fine, I'll save you.
GM: Makarov dispels the trap and brings you all out safely.
Lucy: I thought he wasn't very powerful at all.
Happy: His power only manifests when we try to get ourselves killed before the adventure even starts.