Garrus suffers from a similar timeline problem to Tali. When we first arrive at the Citadel the Councillors mention to Udina (via those hologram projections) that C-Sec is investigating Udina's accusations against Saren. And by the hearing, they find that the investigation has turned up no evidence. Are C-Sec supposed to have gone to Eden Prime, done an investigation and returned, all in the time it took the Normandy to do the journey one-way? Or have C-Sec done the investigation without even going to Eden Prime?
To make matters worse, Garrus (the head of the investigation) mentions that many reports on Saren are classified, as he is a spectre. So the Council launch an investigation, yet withhold lots of reports from their own investigating officer, expect him to find evidence without even going to Eden Prime, and declare Garrus has run out of time after only 15 hours?
On top of which, C-Sec is... Security for the Citadel, surely? What do they have to do with crimes committed on other planets halfway across the galaxy? What jurisdiction would they have there? Are C-Sec actually a badly-named police force for the entire galaxy?