There's a lapse in the story line....... In season 4 episode 17, in the 23rd minute Lincoln said that Michael was born in 1976 but on his tombstone in season 5 episode 1, it was written that he was born in 1974..... Also going with Lincoln saying that Michael was born in 1976 and was 31 years old, his supposed death year should be 2007.......
Aside these the prison break team did a very good Job with this series