When Sucre is waiting for Maricruz, he checks the clock which is at 10:15. But when Maricruz enters the room, the time is now a few minutes before 10:15.
Diabetes 1 requires daily multiple injections with insulin. Also, when a healthy person is injected with insulin they can go into a coma and die (although it's reasonable to assume Michael could have trained his body into building a level of resistance).
Michael stands in front of the judge awaiting his sentencing. The judge states he will be incarcerated at Fox River a level one maximum security facility. Anyone who has been to jail knows that a maximum security facility is considered to be level 5 rather than level 1.
When Veronica is talking with Michael in jail, a guard says that visiting hours are over, and she gets up to leave as if required to do so. Constitutionally, any prisoner is allowed to see his or her lawyer any hour of any day of the year.
The diary in the warden's office shows it is Tuesday 11 April. April 11 fell on a Monday in 2005 (Tuesday in 2000 and 2006). The calendar in Veronica's office circles Wednesday May 11. May 11 did fall on a Wednesday in 2005.
Only a few states actually allow conjugal visits, and Illinois is not one of them.
The bank Michael robs is the Ridgewood bank in Forest Hills, Queens, NYC. It even has a clearly visible and marked NYC Subway entrance when it is shown from the outside. However, the show is based in Chicago and somehow Chicago PD cars respond to this NYC location.
Michael is convicted and sent to a State Prison for the crime of robbing a bank. Bank Robbery is a Federal offense and he would have been sent to a Federal Prison.
In Tancredi's yearbook, "Gandhi" is misspelled "Ghandi".