I was re-watching Leo's video guide, and thought I could add something.

After finishing the three trials, you have to go to the kitchen at the SCUMM bar. Unless I'm wrong, whether the kitchen door is closed or open depends on whether the cook closed it or not before you left the bar at the beginning. You can know that he closed it if you hear the sound of him closing it before leaving the bar.

Similarly, in part 4, the church door will be open if a random pirate opened it during part 1. You can also open it in part 1 yourself, but it loses a bit of time because Guybrush needs to walk up the stairs to open the door and then he needs to walk down the stairs after opening it.