While preparing to shoot the sequence where Leiningen pours oil on himself to repel the ants, Charlton Heston was told that oil would ruin his wardrobe so syrup would be used instead. Heston spent a miserable day on location as the "oil" attracted every insect for miles.
Charlton Heston improvised during the argument scene between Eleanor Parker and himself. It was not scripted that he splash perfume all over her. This move intensified the action and a surprised Parker was able to react accordingly.