Inside the mines, Jessie wears trousers that are much shorter than earlier in the movie, even right before entering the mines.
When Allan bursts through the door of the train car carrying all the Germans, Jessie is nowhere to be seen even though both of them would be standing in the spot at the time.
Just before Dogati fires at Quatermain and Umbopo using Quatermain's own shotgun, the strap on Umbopo's leopardskin is clearly broken. In the next shot it is repaired.
The cauldron changes shape when it starts rolling and again when it comes to a standstill.
The big "stewpot" keeps slopping over with just minor rocking, even though a lot of the water had already been lost from the pot's already having been tipped that far (and farther) by the heroes' previous rocking efforts.
Obviously fake railroad ties when Quatermain is dragged behind the train.
The final explosion is clearly superimposed over the actors even though the blast is some distance behind them.
The pistol that the holy man in the shop first uses fires far too many rounds at once - it's obviously just a small revolver, so there couldn't be more than about six or eight shots in it; no way to shoot that many times in rapid succession.
When followers are crossing the quicksand, it is obvious that what they are stepping on are dummies.
That is an obvious black-haired stuntman when Allan Quatermain jumps out of the mine near the end.
The German troops are largely using the Lee-Enfield No.4 Mk.I rifle, a British weapon not developed until the late 1930's and never adopted by the German armed forces.
Just before Quatermain and Jesse crash the plane, in the view from behind the plane, the blades from the helicopter carrying the camera can be seen at the top of the screen.
When the upside-down tribesman swings towards Jesse, to bring her the crown, you can see the blue lift pole.
None of the Germans on the sandbag car of the train react to Allan when he bursts through the door of the next car.
Virtually all the other characters mispronounce "Quatermain" as "Quartermain".
At 18:13, Dugati (Rhys-Davis) greets Quartermain (Chamberlin) as"Ingles" just as Rodreges greeted Blackthorn, in Shogun.