These guys can help you with that. They also have Pith Helmets, too.
As I’ve mentioned before, they ran out of .577/450 blanks during the film (hence the scene with magazineless Lee-Enfield rifles, and numerous others where the actor is clearly dry-firing the rifle and simulating the recoil, with the sound dubbed in later). Chard and Bromhead are also shown with Webley Mk VI revolvers (not introduced until 1915, but of the style and type of revolvers in service at the time, so an acceptable anachronism), and the soliders had Khaki coloured pith helmets (Stained with tea-leaves, incidentally), not white ones as shown in the film.
The Martini-Henry also had a jamming problem. Since they used black powder cartridges, the guns fouled up reasonably quickly, and the brass expanded in the chamber after firing and would not extract. One of the (unofficial) uses of the cleaning rod issued with all Martini rifles was to knock stuck cartridges out of the breech. The Martini-Henry Mk IV introduced in the 1880s had a longer lever to provide more powerful extraction (by that time they were using stronger brass cartridges as well, which didn’t expand as much), but one of the contributing reasons for the disaster at Isandhlwana was that the British rifles jammed from over-heating. All this became moot in the 1890s when the Brits switched over .303, however.
Zulu is still one of my favourite films, though.