The film provided a variety of hardships for the actors, such as leeches, snakes, stifling humidity, heat, and rough terrain. All of the night scenes were filmed during freezing cold temperatures, which was especially hard on Arnold Schwarzenegger during the latter half of the film, when the mud he had to wear (actually pottery clay) became cold and wet. He was warned it would take his body temperature down a few degrees, and he shivered non-stop, even when they tried to heat him with lamps (it just made the clay dry out). He tried drinking jagertee, a schnapps mixture, to warm him, but that just got him drunk.
Jesse Ventura was delighted to find out from the wardrobe department that his arms were one inch bigger than Arnold Schwarzenegger's. He suggested to Schwarzenegger that they measure arms, with the winner getting a bottle of champagne. Ventura lost, because Schwarzenegger had told the wardrobe department to tell Ventura that his arms were bigger.
The invisibility cloaking effect was achieved with a bright red suit (because it was the farthest opposite of the green of the jungle and the blue of the sky) the size of the Predator. The red was removed with chroma key techniques, leaving an empty area. The take was then repeated without the actors using a 30% wider lens on the camera. When the two takes were combined optically, the jungle from the second take filled in the empty area. Because the second take was filmed with a wider lens, a vague outline of the alien could be seen with the background scenery bending around its shape.
Dutch's line "Get to the chopper!" is Arnold Schwarzenegger's personal favorite catchphrase of all of his films that he appears in.
The black helicopter pilot seen at the end of the movie is Kevin Peter Hall, the actor who plays the Predator. John McTiernan gave him the brief on-screen role, because his "work as Predator was so exhausting."