So far the game only has 2 acts (or rather, a prologue and the first act given the length and depth of act 1) since you're in act 2 you can't lock yourself out of content by progressing too far, only by making certain choices can you miss few scenes and dialogue (or rather, choose certain scenes over others).
None of the character cards can be missed, only side characters (who don't have one) can potentially be missed, usually the ones found through "explore"