 FAIR: The fact that Louis fake phone call to the airport fools Rick  shows that the letters of transit are meant to be used as exit  documents. Yet in the end, the Laszlos board without anybody ever  checking the documents. If once Louis was a hostage he could get the  Laszlos around any exit check, why did Rick insist on the letters of  transit being filled out? He did it to make it "even more official";  the Laszlos would be protected in case there was an unexpected  document check later, either on arrival at Lisbon, or at Casablanca  if someone else arrived on scene and events did not continue as  planned.