I had a bit of a look at some sites which deal with the movie (which, despite the lack of CMPs I still enjoy) and found these details to watch for next time the film is on:
Goofs for
Zulu (1964)
Continuity: During the battle in the hospital, when Hook bayonets a Zulu up against the wall, the bayonet clearly goes under the armpit, not through as the mark left on the wall afterwards would suggest.
Anachronisms: Set in 1879, several Zulu warriors are wearing wrist watches, probably the same ones that the production company paid the extras with.
Incorrectly regarded as goofs: At one point in the film, a bright flash of sunshine can be seen reflecting briefly on what was believed to be a vehicle windscreen up on a hill behind Rorke's Drift. However, Stanley Baker's widow and others who have visited the site confirm that it was impossible to get any sort of vehicle onto the ridge, so there must be some other explanation (probably a spear).
Factual errors: The soldiers wear parade dress uniforms, including white helmets displaying the regimental crest. On active service they would have worn a more basic uniform with plain cork helmets, as depicted correctly in Zulu Dawn (1979).
Anachronisms: The 24th is identified as the "South Wales Borderers". In 1879 the regiment was the 2nd Warwickshire. It did not become a Welsh regiment until 1881.
Anachronisms: Airliner contrails are visible.
Continuity: Chard breaks his revolver to unload it twice as he talks to Bromhead. Both times, the empty shells are ejected.
Anachronisms: The revolvers used by the officers are of WWI issue.
Continuity: When Chard fights the two Zulus who break through the line, a soldier near him is shot and drops his rifle. In the next shot Chard picks up the rifle which has a bayonet attached to it and uses it to fight the Zulus - except that when the stricken soldier dropped it, it didn't have a bayonet on it.
Continuity: When Cpl. Allen is shot while helping Hitch, he grasps the right-hand side of his chest, but in all other scenes the wound is on the left side.
Factual errors: The Zulu chief Cetshwayo did not send his impi to attack Rorke's Drift, and in fact ordered that the installation be left alone. It was one of his half-brothers who ordered and led the attack, figuring he would get a quick victory and impress the king.
Anachronisms: A few of the battle scenes show British soldiers with bolt-action rifles. Apparently there weren't enough Martini-Henrys to go around.
Errors in geography: When Lt. Bromhead (Michael Caine) is seen returning from his hunt, the bearers are carrying a dead cheetah and a springbok. The springbok is an antelope that inhabits arid areas in the northwest of South Africa, and was never present in Natal.
Revealing mistakes: In order to simulate 4,000 Zulu warriors lining up on a ridge, when only 500 Zulu extras were available, long wooden frames were used with 10-12 Zulu shields attached to the front of them with a real Zulu at each end. As the Zulus line up for the final "Fellow Braves" chant, there is one shot in which these shield-frames are obvious.
Revealing mistakes: When Reverend Otto Witt flees Cetshwayo's kraal after the report of the massacre at Isandlwana you can tell that there is a stunt driver in the wagon. The man has a beard.
Continuity: After Pvt Hook breaks into the doctor's cabinet and steals the brandy, he smashes the top off, when he takes a drink the bottle shape has changed.
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