In the very beginning of the movie, where the several men are walking through the forest, you can hear a kookaburra (which is only native to Australia). I know birds fly south for the winter, but not to a completely different country the other side of the world!
The kookaburra has been used as a background "jungle" sound effect ever since I can remember (back to the Tarzan movies of the 1940's). I'm surprised it took over 20 years ("Raiders" was released in the early '80s) for someone to notice this.