Why does he want a second date?

One word: memorable. Yes a first date can go smooth and everything can go as you planned it to, but what's the fun in that. Well obviously in your situation many things went wrong, but sometimes bad isn't all bad if you know what I mean... just different. You both were probably nervous and it showed. I don't know how long it took him to ask for a second date, but you said 'a while ago' which probably means he had to get over the initial shock, but your still stuck in his mind and made a positive impression.