Add option to "flag" or "comment" a card
This is another feature suggestion:
Sometimes the answers presented on a card do not match the posed question displayed on the card's first page (ie. for exam questions). If a learner thinks that there is a mistake or that something is unclear, an efficient way to report this would be through a feature/button that flags a card as eg. "unclear".
Another idea would be to add an "Ask the Author" button that allows the learner to send a comment or a question to the author about the specific card.