Positive Messages/Role Models: Most of the four main characters are brave, stick together, and fight to escape. One main character starts out as a bad role model (carefree, rude) but later develops into a good role model who watches out for his friends and solves puzzles to escape the aliens.
Violence: Many, many people die (including two main characters and two supporting characters) but there is not a single drop of blood or gore throughout the whole film. Instead, when killed by the aliens, people just turn to dust. There is a feeling of dread though out the whole movie, but no jump-out-and-scare-you moments.
Sex: In one brief scene people at a nightclub flirt and a couple is seen making out briefly. A couple sexual jokes in the beginning that will go over kid's heads (example: "Nice shirt" "Yeah, your mom left it in my room last night") In once scene a female character is changing her shirt and is shown in a bra, and a male character sees, though the scene doesn't seem really sexual at all. Two characters almost kiss, but are interrupted by another saying "eww". I wish they did kiss though, it would've been really sweet :)
Language: Sh*t is used throughout (but mostly only by one character) a few uses of b*tch and a*s and ne use of p*ick
Drinking, drugs, etc.: People who are of age drink at a nightclub in the beginning but no one appears drunk and by the end of the movie, so much has happened that the drinking scene seems minor.
Hope this helped, I thought it was overall a great film (despite a few moments of bad CGI) Enjoy the film!