Amicus originally wanted to cast Doug McClure in the lead but he refused so they signed Stuart Whitman. Then Samuel Z. Arkoff of American International Pictures came on board as co-financers but would only make the film if McClure was cast. He changed his mind and agreed to do the film.[1]
The U-boat and ships were models and the dinosaurs and other prehistoric animals were puppets, hand-held or on strings rather than stop motion. The speaking part of Von Schoenvorts was later dubbed in post-production by German-born actor Anton Diffring.
Amicus was to make two more Burroughs adaptations, The People That Time Forgot (1977), a direct sequel to this film starring Patrick Wayne, Sarah Douglas and McClure in an appearance midway to towards the end and At the Earth's Core (1976), with McClure (in a different role), Peter Cushing, and Caroline Munro. All three films were distributed in the United States by American International Pictures