It's hard to give useful feedback for this format given that 3 hours is so tight that frankly having a playable game at all is an accomplishment. I had an issue where clicking too rapidly would highlight the fullscreen button on the Unity WebGL player template for some reason, maybe you set the mouse capture to something weird? Maybe it's just Unity being Unity? Not really a problem since it didn't mess with my clicks, just a weird note.
Good job getting something playable out! Make the buttons a little bigger next time, clicking those tiny icons in a tiny web player was confusing at first!