Thanks for the feedback, everyone! I'll have a new update out shortly that should address a few of these items.
@Jonesy89 - I haven't been able to reproduce the issue with not being able to open the door, but another player who encountered the same problem reported that they were able to open it after walking to the other side of the train and then back again. In the updated version, you will be able to return without opening the door, but that would require restarting the mission.
I was thankfully able to get past this be saving as soon as I was able to recouple the car and then reloading.
Also, I have found a few more bugs:
On reloading an autosave for Dorbi during the caper, the AI for one of the Hellhounds bugs out and just runs around without attacking anything.
While returning to the island where we picked up the train, I ran into a game-breaker. I killed one NC soldier, causing combat to end. I ran into more NC soldiers and killed them. After combat, I found that I could not move or activate the menu. I did not encounter this when I restarted and took everyone on in the same combat; not sure how relevant that is.
Not sure if this is a bug or not, but during combat, spell-like abilities sometime 'bounce' onto other targets; it makes sense for a mage casting from a Dragon line, but not so much for when a mage on a Dragon line is attacked by a Scorpion's poison attack.