Factual error: In the foreground of the Aqaba raid scene, Turks are using a Browning M1919 machine gun, which wasn't yet designed and certainly would not be available to the Turkish Army.
Factual error: En route westwards to Cairo, Lawrence is pictured arriving supposedly at the east bank of the Suez Canal but the direction of sunlight from the right with the Canal in the background can only mean that Lawrence has already crossed the Canal and is standing on the west bank.
Factual error: On his way to Cairo, history records that after crossing the Sinai Desert, Lawrence arrived at the sea at Akaba (which is at the northern end of the Red Sea). In the film he turns left along the beach when he should have turned right (towards the Suez Canal). The scene was shot on a Mediterranean beach in Spain (from where Cairo WOULD be on his left!)
Factual error: There are a number of mistakes with the Vickers guns used by the Arab forces in the film. Quite a few of them are smooth jacketed guns, not introduced until October 1918. Secondly, the one on Colonel Brighton's armoured car not only has the smooth jacket but has a blank fire adaptor very prominently at the front.
Factual error: During the assault on Aqaba, the Turkish defenders are using Lee-Enfield rifles (the same rifles the Arabs have). Ottoman troops were issued Mauser pattern rifles during the First World War.