Richard Johnson 's scenes were all shot in a cave interior in Italy. The shot of him standing atop a waterfall was done with director Sergio Martino wearing a wig.
The first alligator attack doesn't happen until almost 25 minutes in.
Filming took place during the summer of 1979 in Sri Lanka and Italy, and began on 3 June. Filming was originally slated to start on 20 May.
A clip of this movie is on "The 50 Worst Movies Ever Made" DVD Region 1 NTSC.
German Import DVD has a Super-8 Version (German language only), as a special feature on the disc.