A scientist and David Innes (played by Peter Cushing and Doug McClure) employ the former’s impressive drill vehicle, the “Iron Mole,” to travel to the planet's center, where they find Pellucidar, an inner world. This prehistoric area is governed by giant telepathic flying reptiles known as Mahars, who are assisted by ape-like Sagoth creatures and hold primitive humans captive—among them Dia (Caroline Munro) and Ra (Cy Grant). “At the Earth’s Core” (1976) was made by Amicus, a studio that concluded its low-budget film production with three movies based on Edgar Rice Burroughs' works, all featuring Doug McClure: “The Land that Time Forgot” (1975), this picture, and “The People that Time Forgot” (1977). Even though their budgets were clearly limited, I do appreciate those other adventure films, particularly the first one, but "At the Earth’s Core" is a significant disappointment and just plain awful. Cushing's over-the-top, shaky character initially signals trouble, but things become truly terrible when the heroes meet the telepathic flying reptiles. I was hoping to overlook these flaws and enjoy the comic book narrative, however it doesn't really grab you and suffers from its confined locations (the sets look like something out of the original Star Trek TV series). The filmmakers simply didn’t manage to bring the story to life on screen. The film does have some good points: McClure is easy to root for as the lead, Cy Grant is also enjoyable, and Caroline Munro looks fantastic as the cavewoman, although her costume doesn't really do justice to her appearance. Fortunately, they corrected this problem with Dana Gillespie’s more appealing outfit in “The People that Time Forgot.” The film has a running time of 1 hour, 29 minutes and was filmed at Pinewood Studios, located just west of London, England. GRADE: C-/D+

Source on TMDB