When Anna holds a meeting at home with friends, Sébastien walks out to the phone booth by the street to receive a phone call, returning home. All friends are now gone, Anna lying in the dark having re-dressed for the night to sleep asking why he dashed off and hurried back inside, but Anna rushing everybody out and getting ready for sleep would have been a less normal action, especially since Sébastien does not even react to this sudden change at home.
Several times throughout the movie a voice over states location and time the following events will take place. On the arrival of a train in Zurich central train station, it says 14h25 (2.25 pm) but two, perfectly visible railway station clocks show that it's in fact 11.43 am.
When the lead character exits the Munich airport, the big clock above the entrance says just after 15h30 (3.30 pm) but the story's texted time stamp (and spoken voice over in the dubbed version) state that the time is 15h50 (3.50 pm).
At the beginning, the terrorists drive their cars right behind the tram - on a piece of street that is marked not to be used by cars. This would have raised suspicion with the police.