Hatches would be a trap that would be instant death, but the falling animation interfered with the player's movement, and there was not enough time to find the issues, so the damaging part to the trap was cut.
The narrow corridor was a typical design reverse mistake, i.e. rooms were made before the ghost.
The coins were the last thing I added; I realised with one hour to go before submission ended, there was no goal, so the coins were the last thing done. I only just got animating and collecting and had some issues with restarting the game. So having a formal end just wasn't the time there.
Thanks for all the feedback.