95% a great movie

I saw 10 Cloverfield Lane over the weekend.

It's a taut psychological thriller with much to recommend it, and I don't want to put anyone off seeing it.

But - there are two or three bothersome plot points which I haven't seen discussed anywhere.  (I know that one is not mentioned in reviews because it completely gives away the ending.)

Before I get to those, it's the sort of smaller scale Hollywood movie that makes me wonder why small Australian movies can't be as good as this.   The budget could not have been high:  about 90% of the film is set in the bunker, which seems to take only about 3 or 4 different sets.   It's just great because of the acting and screenplay.

Now for the plot issues, in increasing order of seriousness:

SPOILERS SPOILERS SPOILERS

DO NOT READ IF YOU INTEND SEEING THE MOVIE (AND YOU SHOULD)

1.   Why would the bunker be designed so that there is no way to get to the air filtering system for maintenance, or "reset", except via the narrow duct?   There could have been an explanation given - I suggested to my son that maybe Howard had intended having a Hazmat suit that would allow him to go out the main door and get to the vent via its window, but he had accidentally left it in house?  But there is no explanation given, and the need for our hero to go down the vent is very important, plot wise.  With no explanation, the design just makes no sense, at all.  It deserved an explanation.

UPDATE:   I should have known, someone on Reddit would talk about this and explain it, if there was something to explain.   Yes, I overlooked something - or rather, didn't understand properly what was happening - that the thing Howard was pulling on was an access point, but it was covered by something and couldn't be used.   They could have made that clearer than they did.

2.  At the end, is it her car that she is in, and finds the bottle of spirits that she then (implausibly) puts to good use?  If so, is it sufficiently bashed up, and why would Howard bring it there anyway?  This may well be clearer on a second viewing, so I am not sure if this is a problem or not.

Now, out of kindness, I'll even reduce the chances of the main issue ruining the movie for someone who might have accidentally scanned this post:

3.  Do aliens really design ships that forget the fire extinguishers?   Come on, at least in War of the Worlds it took a handful of grenades thrown into the gaping maw to bring down a tripod: that had a bit more plausibility than a flaming bottle of scotch.   I know it must have been hard to come up with a good idea for getting out of this, but still, I was not convinced that this was the best they could come up with.UPDATE:  I see from the Reddit discussion that the green gas the alien ship was spraying around was shown as being flammable, hence the inside of the ship blew up easily.   Hmmm.  Maybe adds some plausibility?

Further Update:   I should explain - I liked the "twist" in a general sense - it was sort of nightmarish in a pleasing way.    I just didn't care much for one detail of the twist.