I wonder if there are any inconsistensies in this game at all. I don't mean nitppickings, no story is perfect, but kinda important ones.
Well, the Tali timing is a bit odd but then, Shepard was unconscious for 16 hours. That doesn't mean that they arrived at the Citadel after 16 hours. For all we know it may have taken a few days to get there.
As a matter of fact, the entire space travel timing thing is completely off in the entire trilogy. For example, in the intro, during the brief time it takes Shepard to walk through the CIC, the Normandy apparently flies from earth (at least Jupiter) to the Charon relay at sub-light speeds from the looks of it.
But whatever,the timing of space travel is always screwed up in SciFi. And whatever Tali managed to do or not to do in a short (though unknown) period of time, while weird, is not impossible.
One other weird thing is that ME1 is supposed to play out entirely in the year 2183. However, there are two armistice days in the game. Once when Ash toasts to it on the Normandy and again when Terra Firma has their little demo in the wards at the end.
What? Did you say no nitpicks? Ah, but this is important stuff! 