Some of these pictures and descriptions may give away plot details that you might not want to know before watching the film.
This is an adventure story about a love triangle between a hunter, a trapper, and the hunter's girlfriend. They all go to Malaysia to capture tigers for a German zoo and to capture "The Enchantress" a big cat that is half leopard/half tiger. Robert Mitchum is Harry, the trapper and Jack Hawkins is Otto, the hunter, whose girlfriend is Anna (Elsa Martinelli), a human "enchantress" who both men compete for. The love triangle only intensifies the fact that trappers and hunters don't get along. Martinelli starred in the Howard Hawks/John Wayne movie Hatari the year before this was made, which also featured animal hunters in the jungle, and the Rampage producers probably used Martinelli to try to cash in on its success.
Rampage is a good example of how a movie can prepare the audience for the appearance of a snake:
In the USA, when planning their trip, Otto tells Harry they are going to the Pahang, the Malay Rainforest where "Tropical flowers grow in the topmost branches, and cobras in the lower ones."
(Now we're ready for some cobras in trees.)
Once they get to Malaysia we see Harry holding a big handgun that he says he is carrying for the cobras that decorate the branches.
(Now we're ready to see Harry shoot a snake in a tree.)
Next we see one of the vehicles they use to travel through the forest pass by a large snake wrapped around a tree. (It looks like a fake python, not a real snake.)
(Now we've seen that there are snakes in trees.)
Shortly after that we see the group walking through a forest directly under a snake hanging on a branch. Harry draws his handgun, shoots it, and kills the snake.
All this was set up and executed so Harry will look like a hero for saving Anna from a killer snake, but Otto tells him that there was no need to shoot the snake. He tells Harry that he and Anna saw the Krait but it was too high to strike anyone. He tells Harry that he's not a hero for shooting it, but Anna seems to disagree and falls for Harry.
Otto calls the snake a Krait, which is not the cobra we were expecting, but a different kind of venomous snake. The "Krait" is another fake snake, but at least they decorated it with a banded pattern, like you'd see on a real Krait.