Trivia: In the Tangier chase scene, Nicky and Desh are seen pushing past the citizens. These are not extras, Tangier was too crowded and the flow of the people was hard to control, hence the two actors are genuinely pushing through the crowd.
Trivia: Although you can't see all the details on Nicky's computer when watching the film (since it's cut too fast). You will find that when Nicky looks-up Desh Bouksani on her laptop, and finds that Desh is "the Asset", there is a list of code-outs (from Blackbriar) that are quite interesting to read. The Contact Code List is: STONE BLUE: Terminate with extreme prejudice. RIVER RED: Discretion required. GRASS GREEN: Accidental death. ALPHA PAPER: Suicide. KEY BRAVO: Build case termination scenario. BLUE SKY: Proceed. LOOK BACK: Contact handler. MOUSE TRAP: Case compromised, exercise caution. INTERSTATE: New target location. FIRE LINE: Special weapons pickup required. TALK DOWN: Case action on hold, do not proceed. LOCK STEP: Follow target, observe and report.
Answer: Knowing Bourne, he must have had a keycard on his person. Remember that Landy guided Bourne back to the CIA New York Headquarters; she could have easily slipped a keycard in the Taxi Cab when Bourne was being picked up at the airport. All he would have to do then is avoid being detected by using the fire exits (hence going through the back).
Jason Riley