Match History crit damage calculation bug?

I was looking at my match history and noticed something weird: History claimed that my largest critical strike did 735 damage and I cannot figure out how I could have reached that high damage. I had 101 base AD at lvl 18 and my items were: Mortal Reminder (50 AD), Hurricane, Gunblade (40 AD), Essence Reaver (70 AD), Berserks and a Vamp Scepter (15 AD). Total is 276. This should imo cause maximum of 552 damage on an unarmored minion. My team had Janna, but her shield adds around 60 AD max to ADCs damage, ie: 552+2x60=672 damage, which is still not 735. Is Match History crit math somehow bugged, or is my own math off somehow (link to the match to see the details if I omitted something)?

Edit; Ah, I didn't notice that Janna has got Athene, and I forgot to add Athene's Dissonance to her AP. She got 250% extra mana regen, so that is +50 AP, for total of 180*1,4 = 252 AP, Shield grants 40+10% AP = 65 AD. 65 x 2 = 130, this added to my own crit damage of 552, results in 682.. which is still not 735. This bugs me. :(