Absolutely no sex or nudity in this movie. Why would people call it "mild" is beyond me.
Sex is implied a few times, and many conversation regarding the subject, but no actual nudity or sexual acts are shown.
A couple are seen in bed a few times, and in a bathtub together, but only shoulders and arms are seen.
A few scenes of couples kissing or making out.
A threesome is shown with two girls and a guy making out and then later waking up in bed together.