Even though John Hurt received top billing (his name is shown even before the title of the show) he really only appears in episode 1. Both his 5-second appearances in episode 2 and 3 are in one of Paul's visions.
Sietch Tabr, as shown in this episode is above ground. This is a change from the novels, in which all sietches were located in caves, below ground.
Goof: The window in Leto and Jessica's bedroom is open, as can be seen by the wind moving her hair. On Dune windows would never be open, because too much moisture could escape.