When did Michael have time to get a divorce ? *spoilers*

Surprised no-one mentioned this one yet, go back to season 1 he had a marriage of convince as part of his escape plan so she could bring him the credit card.
At the beginning of final break him and sara are getting married, but they mention at the reception after that it had only been a few weeks since the exoneration.
Now he had a couple of mths between seasons 3 and 4, but we are to believe he was tracking down whistler and gretchen, and he believed she was dead so probably wasn't really thinking much about his divorce.
So you know what with escaping from prison, being on the run, being locked in another prison escaping, taking down the company, when did he find time to sort the necessary paper work ? He'd never be able to annul the marriage, and if he did she'd be deported.
Bit of a plot hole don't you think ?