
Iago and his wife appear to be having sex in their bed for a second, though they are fully closed as far as the audience can see. This is not entirely clear, however.
The very brief scenes of sexuality are the sole reason for the film's R-rating. Nevertheless, that may have been a bit of an overreaction. The film is approved for 12 and older in the UK, and a PG-13 would probably have sufficed.
Othello and Desdemona are shown having sex on their honeymoon. This does not occur on-stage in the play, but it is depicted in this film. We see them undressing, with a quick glimpse of Desdemona's bare breasts. We then see them from the waste up while they have sex, with loud gasping and motion that goes on for several seconds. The scene starts at the 31-minute mark in the film, and it lasts for just under two minutes. It can be skipped without missing anything important to the movie at all.
Two men listen to a man and woman having sex inside of a carriage. Very little is actually shown. This is entirely irrelevant and is not in Shakespeare's play in any way. However, it probably won't even be noticed by children, since it is only in the background and dialogue is taking place during the whole scene.
After being made to believe his wife is unfaithful, Othello has nightmares of Desdemona having sex with Cassio. In one dream scene, you see them having sex with Desdemona's bare breasts visible for about a second or two. However, the scene cuts in and out rapidly, obscuring anything too graphic or explicit.