The German Mauser C96 is the weapon used by the Turkish officer to wound Lawrence during the takeover of the train. These guns can be seen in the hands of other characters, including the Turkish Bey (José Ferrer) while in Deraa. Several Turkish officers during the attack on Aqaba can be seen using unidentified revolvers.
The Lee-Enfield SMLE rifle is used by the Arabs and British throughout the movie. Turkish soldiers also use these weapons in several scenes, interchanging with Mausers, presumably depending on what country the scenes were shot in (Jordan, Spain or Morocco) and the availability of the rifles. While likely not intentional, this is not entirely inaccurate as the Turks did re-issue the SMLEs captured at Gallipoli.
Several of Lawrence's bodyguards towards the end of the film are armed with some type of Jezail musket, a commonly used musket (notable for its rounded, forked stock and long barrel) found in the Middle East. They can be found with all types of muzzle-loading ignition - matchlock, flintlock (often Snaphaunce or Miquelet), and percussion.
Browning M1919A4 machine guns are seen used by the Turks in the first train attack scene. This is an anachronism since the movie takes place from 1916 to 1918.
The Arabs use the Vickers Gun when they assault the trains. Interestingly, Lawrence asks General Allenby earlier in the film for instructors for the Lewis guns he had requested, it seems he was provided with the Vickers' instead, at least as far as the film shows.
Lawrence and the Arabs conquer Aqaba to eliminate the threat to supply ships, that the sea batteries possesses. Mentioned earlier in the film by Brighton as being 12-inch guns, they are non-firing mock-ups.
The Turkish planes used in the raid on Feisal's camp appear to be disguised De Havilland Tiger Moths, a biplane used by the British Royal Air Force from 1932 to 1959, and the default biplane for British movies.
