Here's a few that have caused controversy.
Adding incest into the mix? As if to show that the trope had been averted only because the writers thought they could push the envelope further, they then brought on Eve and Julian's actual child, a named Vincent who had been living in Harmony as the established character Valerie for several years , who proceeded to have an affair with his uncle Chad both as Valerie and as Vincent, at separate times , rape his half-sister Fancy, and seduce and become pregnant by his own father.
The filmmakers clarified that the scene was mostly shot separately, and they used special clothes.
Its certainly not helped by the Bene Gesserit's clear intention to find a way of bargaining for a way to get Paul and his sister to produce an heir.