Harryhausen got in over his head with the stop-motion humans! :D
He did a good job, yes, but even he couldn't make them look natural. Perhaps the shots should have been from a greater distance... I'm speaking of the scene where they approach the golden fleece.
By the way, I loved Medea's reaction shots during said scene, haha. The shots were silly, of course, but the love is genuine.
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Ph'nglui mglw'nafh Cthulhu R'lyeh wgah'nagl fhtagn