food for thought
These are just a few little things that fall under the category of "not really all that life shattering" but I still felt were interesting enough to warrant mentioning somewhere. You know, the story inconsistencies, the wild theories, the references to bad movies...
Date of Birth
I'm not the first person to notice, but there are actually two potential dates for Anna's birthday. The first, as seen to the right on her patient history from the hospital, is April 13, 1985. However, when Sam later tries to find Anna's grace by looking up meteorites that could have actually been her falling from Heaven, the one he finds that fell "nine months before Anna was born" nearby her hometown he claims was sighted in March of 1985. By that account, Anna would actually have been born in November or December of the same year, which is quite a ways away from April.
Personally, if I had to pick one as the more "official" I'd go with her birthday falling towards the end of the year as Sam mentioned, as it actually came from the dialogue so you can't miss it. The date in April, on the other hand, is something only noticed by those of us who take the time to hit pause and read through her medical file.
Lay back and think of Jesus
In the special features of the Supernatural season four DVDs there's a discussion on Lilith, who is believed by some to have been the original wife of Adam. The reason the relationship failed was that Lilith wouldn't submit to his will, thinking herself his equal (can you see why she's become a sort of feminist hero?), and one of the many rumoured ways she displayed this was through refusing to do it missionary style. In other words, Lilith wanted to be on top.
So of course, with the way my mind works, while watching Dean and Anna's sex scene I wasn't thinking "man that's hot!" but instead I was noting that Anna quickly took charge of things and wondered if that was intentional after what they said about Lilith. It probably wasn't (they were probably thinking "man that's hot!" like a normal person should), but yes, something to note: fallen angels don't do it as God intended.
On the topic of Anna and Dean having sex in a car, if you didn't realize it Anna's hand on the window was intentionally a throw-back to the sex scene between Jack and Rose in Titanic, which came as no surprise to me since Supernatural loves to borrow imagery left and right (all in good fun). What was completely unintentional but still interesting to note (well, at least I think so) is the shape that Anna's hand makes in the steam, which actually looks a hell of a lot like an angel. But yes, a complete fluke (when asked about it Julie McNiven wished she could say she had intended to do that).