After going through I suppose thousands of flashcards with my eldest girl who is coming of 3 years old, I realized that there is no one strict formula for the type of flashcards to show to an infant or toddler. My advice to parents is to let your imagination run wild and do up whatever topics you feel is fun for your child.
I do however, encourage that parents do not plaster all information within a single card. Keep each card clean and simple. Illustrations and words together do not work as well as presenting them separately. Speed of flashing is something we can work on as well. To truly activate the right brain's abilities, we have to flash real fast and thus triggering photographic capabilities.