All the tiny detailed scrutiny into Jay's testimony fails to see the forest for the trees. Somewhat understandably, because on one hand, Jay's testimony was the key evidence in the case, but on the other hand, the inconsistencies in his story are as far as I can tell the only place anyone could possibly point to reasonable doubt.

I see three possibilities for the inconsistencies in Jay's statements.

1) He is covering for his own involvement, or not wishing to involve friends and/or family members who might have their own reasons to not want policy scrutiny.

2) It was six weeks later when he was first asked about it. He could just be trying his best to give an honest recollection. The idea that after "a big event" that person will remember perfectly other, non-essential aspects of their day is hogwash.

3) Some weird implausible theory where Adnan by sheer coincidence lends his car & phone out, and later spends the day hanging out with, a guy who independently is involved in murdering Adnan's ex-girlfriend for reasons unknown. Then, before he even talks to police, Jay fingers Adnan to several people because he's both a criminal mastermind while also being too stupid to just memorize one story and repeat it.

Explanations 1 & 2 (or a combination of both) are entirely plausible, and in fact, it would almost be more suspicious if there was none of that going on.

Meanwhile, explanation 3 has no evidence behind it, is extremely unlikely, and opens up a number of other very difficult to answer questions, like what was the possible motive for the killing and who else would Hae let into her car other than the friend of hers asking for a ride that day (conveniently because he made sure he didn't have his own car)?

Long story short, I totally understand why the jury was not bothered with irrelevant discrepancies in Jay's story, and while I realize we all are analyzing every detail of the case ad nauseum, we shouldn't be bothered by it either.