Common Sense Note Parents need to know that DUNE is a 1984 adaptation of Frank Herbert's famous science fiction novel of 1965. It is filled with fantasy violence of all types including torture, gore, fighting, weapons, and some generally scary and disturbing imagery (including the quasi-torture of a cat and a rat and a young girl wielding a knife). The underlying theme is about a 'chosen one' who never has to make any decisions for himself, and then simply declares war on his enemies. 
Characters in the movie are after a drug called 'Spice,' which is shown to be powerful enough for men to go to war over. Young science fiction fans may want to see this (as well as a 5-hour TV miniseries remake from 2000), but the immense novel is compressed to the point that the movie is almost nonsensical, and the visual effects have dated badly. Director David Lynch also tries to put his own personal spin on the material, which will at least make the movie more interesting to Lynch fans.
The Alternative Edition Redux uses most elements of her narration from the Theatrical Edition, plus selected audio edits from her Deleted Scene. * The male narrator including the painted prologue from the Extended Edition has been deleted, but parts of it have been reworked into two new filmbooks about the history of the universe, read by Paul Atreides during the film.
Sexual Content Paul and Chani are seen in bed together, with naked shoulders, but nothing else. Sting appears nearly naked, wearing only a tiny speedo, and Lady Jessica wears a sexy nightgown in some scenes. Characters flirt with her and tell her how desirable she is. Violence The movie is filled with fantasy-style battles as well as some burning flesh, spurting blood, gore, and torture. We see knife fights (with stabbing), poison gas, kicking, biting, and punching, a severed head, scary monsters, and scary noises, and a special kind of voice-operated laser gun. We also see a scary floating killer hypodermic needle (a 'hunter-seeker').
There is a scene in which a rat and a cat are strapped into painful-looking positions and locked in a cage. Notably, there is a young girl character (played by Alicia Witt) who wields a knife. Language Not applicable Social Behavior Under all the sci-fi names and gizmos and ideas, DUNE is essentially just a war movie. The hero, Paul, is apparently 'the chosen one,' and thus he never really has to make a choice; his destiny is laid out for him. When he finds his place, the first thing he does is declare war on his enemy. The objective is to free the desert planet Arrakis, but it's arguable whether or not the end justifies the means.
Consumerism Not applicable Drugs / Tobacco / Alcohol Everyone in the film is after 'Spice,' a powerful substance that allows users to travel through vast amounts of space and to live longer. There are also side effects, such as glowing blue eyes. The 'Spice' is never demonstrated as being dangerous, but the behavior of the characters around it is a bit like drug dealers on earth. There are also some 'drug trip'-like sequences.