So far I've only had a chance to play a couple of times and both times I ran scenario one. As I was reviewing the other scenarios for another game this weekend I noticed something about the way the doors line up on the tiles. In the first scenario it seems that every door that a person can go through matches to another door marker on the next tile, otherwise those doors that do not meet up are blocked off. In the other scenarios this doesn't seem to be the case however. Am I missing something, or does a door only have to be on one tile to be accessable unless otherwise specified?

As far as I'm aware, the only scenario that has doors that lead into walls is scenario 5, and that is due to a few misprints with that scenario's map. Normally, all doors should either lead to other doors, to the open end of a corridor, to an outside area, or be sealed.

For instance, scenario 4 has the corner hall tile connected to the gallery tile. The end of the hallway doesn't have a door, but the gallery tile does. Now, logic would dictate that you should be able to go into the gallery from the hall, but based on the fact every other door seems to connect I'm just curious if I was missing something. Especially since there is a door on that same map in hallway 3 that is not blocked off, but leads to the stairwell in the attic where there is no door on the other side.

If there is a door on either tile the door is functional. The blocked door markers are used to lay over 'single doors' that are not meant to be used in a scenario... this wouldn't be done if the presence of only one door meant there was no door.

*some* Hall Tiles do not end with doors but with thick grey lines. These work the same way that grey lines between spaces work, so you can count them as doors when looking on how to enter the room.
If there is a wall (thick brown border) between a room and a door on the other side and you are NOT playing Story 5, the map was set up incorrectly.

Why do some Hall Tiles end with grey borders instead of doors?
To allow the creation of long hallways where players with ranged weapons / spells can aim at monsters further down the hall.