This is a nit that was pointed out in the DVD commentary (yes I know that's cheating), the abortion clinic has one door on the outside, but two doors on the inside.
Why would it be cheating? You don't have to be the person who personally spotted a nit in order to relate it. For every episode of Voyager and Enterprise whose nits I posted when they were in first-run airing, I listed the nits pointed out by reviewers Jamahl Epsicokhan and David E. Sluss on their sites.
It's only cheating if you credit someone else's find for yourself.
I caught up with this on HBO the other day. An OK pic, but over-rated in the extremus. Not enough of her dad, played by the great JK Simmons. Plus, (minor Spoiler Alert), once Juno gives birth, she sure drops the extra weight she gained real quick.