When they are all walking through Express Train to Philadelphia tunnel, you will notice every so often the flaming torches will almost be going out, when the camera changes the torches will be re soaked in oil or paraffin and fully lit again.
Rachel says the amplifier would power anything within a half-mile radius. Monroe says it could be used to power tanks and jets. While it could power a tank or a jet, the weapon would have to be used within a quarter mile of the target unless the amplifier was on board the tank or jet. If it was on board the tank or jet, this would be a bad tactical use as it could be lost in the event of a mechanical failure.
The Characters in the story are said to hallucinate from the lack of oxygen, however a lack of oxygen (hypoxia) does not cause hallucinations.
When the Group joined by the Rebels are down in the tunnels they begin to hallucinate because of the lack of oxygen. However it takes at least half a day for the oxygen to run out in a 10-by-10 metre room containing 10 people (which is about the number of their group). In the show they are trapped in an abandoned train tunnel which is definitely much larger than a 10-by-10 metre room and haven't been down there for more than a day when they begin to hallucinate. In theory they should be able to survive down there for days.