Early on there is a scene of two extras making out outside a bar.

There is a scene of two people "making out" in which the woman has her shirt partially lifted, but the two are interrupted before anything is shown.

There is a scene when two of the Characters are in bed, it is implied that they are nude and have just had intercourse, but they are covered in blankets up to their shoulders.

There is a scene where one Character extorts a women into having sex, which is not shown. Later you see the strap and shoulder area of the woman's bra as her shirt is unbuttoned, but nothing explicit.

Some sexual dialogue.

All in all the sex and nudity alone would only account for a PG or PG-13 ratting.

There are two scenes with blood; in one a man is pushed against a fence and has his face cut, and the other a man has a dart thrown threw his hand. Both scenes are brief and mild.

There are a great deal of "f words" and crude slang for male and female genitalia, and liberal use general profanity. It is due to the profanity that the movie is rated R.

The Characters are regularly drinking beer, usually in a pub type setting or whilst camping. All characters drinking are of age.