@Fire Fist:
He could just be there because Jinbei's there, or as an escort for Ace. Where else would he be, at a time like this? Everyone else in the marines of significant importance is at Marineford, getting ready for Shirohige's fleet. Unless he's a lazy bastard (which he hasn't shown to be; that's Kuzan's thing, and he's at Marineford and ready to fight), he's probably at Impel Down killing time while he awaits his orders to transport Ace.
Yeah right, then he'd be doing a really sloppy job focusing on fodder guys. Besides, just because we didn't see him at Marine HQ it doesn't mean he isn't there. Oda just gave us what we are familiar with, since that alone was enough. No need to wast Sakazuki's real time introduction in such small panels. When he appears it will be with a big bang and with a full body shot plus the discription box. You can't put all that in the pages of the last chapter.
@Ivotas: Well either Oda made an error, or we are over analyzing things. I will look into it.
Doesn't even have to be an error. Just a lack of over exaggerated precision. I actually think it all works well as it is now. Could have been more precise with pointing towards the Gate first and then from the Gate to the current precision. But in the end it doesn't strike as something that requires such an amount of detail. Just what I think. Those current arrows are the more important thing by my book since it explains a bit of the world. The other thing is just a route summary.