The flip card widget is 508-compliant, just like any other widget.

https://helpx.adobe.com/captivate/help/creating-accessible-projects-captivate.html

Hi! Yes, the flip card interaction can be made 508 compliant. Use the ‘Accessibility’ settings on the right navigation panel to set tab order, include accessibility text, and select the speech agent languages along with other features.  

I first need to know which version you are talking about? Can you check the full version number under Help, About Captivate please. I suspect it is a version 12, but want to be sure.