Factual error: When we see Kyle as an adult, images of his several pill bottles are flashed on screen. One of these says "anti-psychotic" and is later referenced by a police officer; the other says "Take every 4 hours for depression." Psychoactive drugs would never have their purpose on the bottle, to protect the patient.
Factual error: Towards the end of the movie when Kyle, Michael and Kat are all in the lighthouse, they drop a green lightstick which then breaks in two. However, in reality, these lightsticks are virtually unbreakable as they are made of hard durable plastic which is why they are used by survival experts, divers and the emergency services. They are non-heat producing and work on a biochemical reaction - another reason why they are so difficult to break is to keep these chemicals in.
Factual error: Towards the end of the movie when the power has failed, the emergency lights come on. After about 10 minutes someone is heard to say that they only have a few minutes of light left. Emergency lights in this country (England) are required to last 3 hours non-maintained, I'm sure that in America the characteristics of the lights must be similar, e.g. the emergency lights should be on longer than 13 minutes.