A character near the beginning of the movie is on the radio and gives a time check of "O Ten Hundred". A preceding "0" is only added to single digits times, e.g., 0100 - 0900.
The term "singularity event" is defined as a one-off incident which can threaten the Earth's existence. Not only has the creature apparently emerged on two previous occasions, the (not "a") singularity is actually a hypothesized point when artificial intelligence outpaces that of humanity's. It is also used in general relativity theory to describe certain gravitational or spacetime events.
A previous comment suggested carbon monoxide should be the killing mechanism instead of carbon dioxide, but there is historical record of extreme levels of carbon dioxide being released from the earth via earthquake or volcanic activity. There are also records of a carbon dioxide infused lake in Africa "burping" and laying waste to all wildlife for several thousand yards surrounding it.
Throughout the movie, they are referring to carbon dioxide (CO2) causing deaths by just going to sleep, floating 3 feet above the ground, etc. All of that describes carbon monoxide (CO), not carbon dioxide.
During the violent tremors the cast generally stagger about or fall over; however, in one such scene a person in the background can be seen strolling unhindered across the road, making it clear it's the camera, not the ground, which is shaking.