When the yeti like creature first speaks, actor Carel Struycken is speaking his native Dutch, and not as John Neville's character surmises, a 'Tibetan dialect found in the high Himalayas'. His words roughly translate to "I couldn't do anything about this, I just happened to be in the neighborhood, and..."
Credited for 'Special Vocal Effects', voice actor Frank Welker uses his "Dr. Claw" voice from L'ispettore Gadget (1983) for the mysterious villain, who is credited as "Dark Prince" in the cast list and played by stuntman Alex Daniels.
Despite using the title of the 1864 novel "Journey to the Center of the Earth" by Jules Verne, this modern day version has practically nothing to do with the book.