Corey Burton, who voices the Critters, also came up with their language, which he described in interviews as combining elements of French and Japanese.
Although promoted as New Line's answer to Gremlins (1984), the screenplay had been written and bought before Gremlins was announced. Herek had based the screenplay on a nightmare he experienced as a child.
The prop department used merkins from the local 'nice 'n' naughty' for the Critters.