Gale's intro is actually more of a plot hole, imo, than Astarion.
He says, "Last time I saw you, you were in a crucible's worth of blood - an intellect devourer nibbling at your ear."
???
When was I at any point in a "crucible's worth of blood" with "an intellect devourer nibbling at my ear?"
I wake up in a flaming chamber with no intellect devourers or even carcasses of them. I fight imps and maybe a devourer or 2 IF I make the wrong choices. Never am I wallowing in blood with a devourer.
Astarion I could see being any of the pods, as mentioned, in the many pod chamber. Even if you don't go in, the door opens and closes semi-frequently because of the devourer running around. Wyll and Mizora and who knows who else could have been in there. Even Karlach is explainable, as you don't get to explore even half of the overall ship - though DANG she was infected fast. She sees the nautiloid, flies up to it presumably with magic wings, and BAM. Tadpole crawls up into her head. ??? Wow. Now that's something.
Unless they're going for her not being actually infected, which is possible. They never really say she has one, and you do connect with people who don't.
But if Gale was in there in the many pod chamber, his line then makes even less sense. At no point am I lying on the floor in that chamber. The only place his line makes sense at all is if he was in the original pod chamber. But then... Which pod was his?
And especially in a multiplayer party of 4 scenario, there aren't any pods for Gale, Lae'zel or anyone in that chamber. Just your party of 4.
Maybe they should add more pods in there.
But then... I've been told... Larian isn't going for exact, accurate anything. Though you can travel foot by foot, meter by meter through everything, the map is actually abstract. It represents the location. It isn't everything that actually is there. So, with that in mind, other pods exist, you just can't see them. Other people and creatures exist, in your imagination.
Yeah, I know. They get super detailed in some ways and are super abstract with others. Pick up knives and spoons and forks, like that's important, but don't include actual story elements for consistency. Makes no sense to me. The origin characters are just somewhere on the ship somehow, campsites just exist somewhere in dungeons you have explored wall to wall, but you can find and pick up useless brains or bones or whatever that have no meaning or purpose. I don't get it.