On 13 April 1975, while class is in session, Tarek watches the ambush of the bus from the balcony of his school in Christian-dominated East Beirut. 13 April 1975 was a Sunday. Schools in East Beirut are closed on Sundays.
In one scene when Tarek and Omar can't find May and sit down to talk, a Peugeot 505 appears in the background. Peugeot hadn't released their 505 model in 1975-76, the year at which the scene is supposed to happen.
Chevrolet M1008 Commercial Utility Cargo Vehicles - a militarized 5/4 ton version of the third generation Chevrolet C/K pickup - are seen in the movie, which was supposed to have taken place in 1975. The Chevrolet M1008 did not enter production until 1984.