What happened to the alien tracker hound after Michelle destroys the alien craft? It was running after her when she tried to make for the farmhouse. Did the poison gas kill it offscreen?
Both the ship and tracker hound seemed half fleshy, half robotic in appearance. Perhaps the dog was being "piloted", or at least influenced by the ship/by the beings piloting the ship, and once it blew it, the tracker hound was no longer active.
Or for a more brute-force answer, possibly a chunk of the ship or even Michelle's car landed on the thing.
A guy that paranoid probably isn't too hard to accidentally wake up.
He refers to his bedroom as his own private off-limits area and it's the only room (Apart from Michelle's cell) with a door; he probably just locks the door at night. Plus, until the end neither Michelle or Emmett was completely set on killing him, they probably didn't consider that option (Even the plans they do have involve incapacitating him until they find some kind of authority.
Unless they're psychopaths or sociopaths with homicidal tendencies, most people tend to try and avoid murder to solve their problems if there's another way to do it. Even under the circumstances it's a pretty drastic thing to do.
Shouldn't the corrosive liquid Howard used have eaten through his shirt when he fell in?
How was the air filtration room locked from the inside?
The same way the inner door was locked from the inside. Remember, there was a hatch that would have allowed Howard or Emmett into the room, but something was blocking it. Prior to that scene, there wasn't anything blocking access to the hatch, thus access to the room and the door.
To expand on this, the original poster was likely asking why the passage into room with the filtration unit was locked. It wasn't, something had fallen and blocked the door from being opened.
Why would Howard build a bunker that did not give him access to his own air filtration unit? For all of his planning, he'd have been dead within days had not Michelle been there.
He had access to the filtration unit through a hatch, in the movie you can see Howard trying to open it, but apparently something was blocking it.
He didn't build a bunker denying him access to his air filtration unit. There is a whole scene before he sends Michelle into the ducts in which he explains that there is a hatch that he would normally use to get into the room with the air filtration unit. During the shaking scene, something in that room had fallen down and was blocking that hatch from opening.
How exactly did Howard get out of the ventilation room after he padlocked it from the inside? There's no way out of it except the ventilation shaft, which Howard admits he can't fit through.
How did people manage to ask the same question three times in a row all in a different manner?
Who took the polaroid of Howard and the abducted girl? Polaroid cameras don't have timers.
Polaroid cameras are available with self-timers, such as versions of the Spectra.
That wasn't the girl he abducted, that was his daughter.
There are two possibilities involved with the girl in that picture. First and foremost, it was his daughter, and his ex-wife took the picture. Second is that it's a different girl that he kidnapped. If it's the latter scenario, then it was likely a camera with a timer or a button extension that let him take the picture from a distance.
Either way, Emmett confirms that the girl in the picture isn't actually his daughter.
Why did Howard chain Michelle after rescuing and nursing her?
