There is only one sequence of actual sex and nudity. This is when Ethan Hawke's character was attacked in bed and injected with a substance. All other references currently listed are suggestions of and not actual.
The sexual activity portrayed here is shown by context and without strong details.
In addition, there is also a very brief shot depicting a couple having sex in a car where their sexual movements are visible.
It is suggested that a child character was abused or raped but it is not shown.
One character has sex in a dream sequence; very obscure and play as an horror moment, not a sexual one. (woman side breast and upper butt briefly show)