Displaying an icon or some sort of indicator next to a card title to indicate that a user can click on something on the card to drill for further detail would greatly improve the user experience on a dashboard. Currently, a user has no idea what will happen when clicking on a card in a dashboard as there are at least 4 different options that can be configured.
Also, the designer of the dashboard has no way to quickly look at a dashboard and know what will happen with each card on the dashboard unless they edit the dashboard and check the interaction of each card, which is a very tedious process.
A visual indicator would greatly help the user experience for both the users of the dashboard and the designers of the dashboard.