You did find most of the easter egg content! There was one really weird one that nobody has noticed yet. That bug with the last boss is an unfortunate symptom of some hackery I had to do for the sake of time; he is a lot bigger than his actual hitbox is, so if he isn't directly in front of you, the attack whiffs. We also made everything really easy on purpose; we didn't want people to get stuck. Some other weird hackery on the last boss, to get him to feel a little better, without building additional functionality, he actually does an invisible ranged attack from 3 grid squares away, lol.
Thank you for the feedback, and thanks for playing our game!