Police scam at Nosy Be Airport
Getting through immigration at Nosy Be can take a long time but a 'helpful' police officer will assist you for a small bribe – 20,000 normally works.
They then give you a 72 hour stamp and assure you that there will be no problems with leaving but make sure you remember the officer's name.
What the police do not appear able to do with this short-cut route is arrange for a proper pasted-in visa.
On departing they will ask about overstaying your visa at the first police check but tell them that officer 'X' assured you it was OK. At the actual passport check they will again say it is out of date and another small bribe will sort the problem.
This has happened both to me and a friend without any issues.