Chrono Trigger Prism Cards
From Chrono Compendium
General Information
Prior to Chrono Trigger's release, several cards depicting character artwork and scenes from supposed beta versions were released; these seem to offer further insight into stages of the game's development prior to the Prerelease -- however, it was commonplace for developers to simply produce mockups of scenes and submit them. A mockup is not an actual ingame screenshot, though it may use graphics from the game; it is a fabricated work. The various differences apparent in the prism scene cards suggest that they are mockups, though some may be actual screenshots.
From: Chrono Trigger Prerelease
From: Merchandise