Dr. Francis tells Murdoch that sleeping sickness is caused by the tse-tse fly.
The episode takes place in the late 1890s, but it wasn't until 1903 that David Bruce discovered that the tse-tse was the vector of the disease.
Although it is true that amphetamines were first synthesized in 1887, it wasn't until 1919 that methamphetamine, a stimulant, was developed by a Japanese pharmacologist, more than twenty years after this episode takes place.
The episode takes place on the eve of the Second Boer War in late 1899, but the troops are all armed with the Short Magazine Lee-Enfield rifle or SMLE, which was adopted in 1902 and not produced in quantity until 1903. Commonwealth troops in 1899 would be armed with the earlier "Long" Magazine Lee-Enfield or its predecessor, the Magazine Lee-Metford, which was still in the process of being phased out; these rifles have projecting barrels rather than the SMLE's distinctive blunt nose cap and bayonet mount. However, as the later SMLE was used in both World Wars and was consequently produced in vastly greater numbers, it's far more readily available to film armorers than its predecessors.