I submitted my application to an Ivy league college a few days ago, but I just realized that in one of the supplements, I talked about a few literary "alumni" of the college that weren't actually from there. (Oops. I've proofread the essay a thousand times without noticing that.)
However, it wasn't an overly major part of what I was trying to express, and the rest of my essay was fine.
So I'm wondering if (and if so, how much) this will hurt my chances of admission.
Forget it. Not a big deal. If schools rejected every applicant whose application had a mistake or typos or other minor errors, their selectivity ratio would drop like a rock, and they’d loose lots of potentially excellent applicants. And what would you do about it, if it did matter? The application is submitted and sending a follow up email just draws attention to the error.
Nothing you can do now. Don’t worry about it. It doesn’t define you as a person or student, so if you don’t get in, it’s not because of that.
It can’t be fixed now, so don’t worry. I doubt it’ll hurt your chances.