B&A: Can you do this in first-person writing?

Yes you could. It's a bit weird, and so it doesn't stand out you might want to do this a couple times and make a style of it. I read a book (and I'll tell you the one if you want) that was first person and did some pretty strange things with it, almost like it was omnipotent. Like in this once instance this guy is telling the MC about why he's covered in blood, and he spews some heroic story about putting a deer (or was it dog?) out of it's misery. And it's a very convincing story, but then it would say something like "But I would find out soon enough that it wasn't dog blood on his shirt, but human" and then it would jump back to the story. The book was kind of slow moving, and the character was pretty gullible, so I think the author did this to sort of make this suspense out of anything. It worked for the novel, and it could work for yours.