A turn of the century wild west show struggling to make a living in Mexico comes into the possession of a tiny prehistoric horse. This leads to an expedition to the Forbidden Valley where they discover living dinosaurs. They capture one and take it back to be put on display, leading to inevitable mayhem.
Unfortunately the movie The Valley of Gwangi is not yet available on HBO Max.
| Writing | William Bast | Screenplay |
| Directing | Jim O'Connolly | Director |
| Camera | Erwin Hillier | Director of Photography |
| Editing | Henry Richardson | Editor |
| Visual Effects | Ray Harryhausen | Visual Effects |
| Sound | Jerome Moross | Original Music Composer |
| Production | Charles H. Schneer | Producer |
| Crew | Julian More | Additional Writing |
| Art | Gil Parrondo | Art Direction |
