Overall - Mild content
Violence: Mild - There is a brief sequence where one of the main characters bloodlessly kills a number of human-like creatures (this is very brief and mostly off-screen). Another main character also becomes wounded after receiving a scratch from a large tiger-like creature and another character is bloodlessly decapitated. A head-but is administered by one of the main characters to another character and there are various battle scenes (one of which includes a main character's hand being cut of by a 'lightsaber') where creatures are killed bloodlessly. A character is shot and killed by a dart (we hear the noise but to do not see the dart). None of these scenes have a major impact and are only mildly intense.
Sex/Nudity: None (Although there is an ongoing 'forbidden' relationship between two of the main characters which is only mildly intense in some scenes).
Horror: Mild - A character witnesses the death of his mother (she is not killed but is dying from becoming too weary after being captured) but despite being the most emotionally intense thing in the film this is still brief and discreet. The characters are menaced by (and, in the case of one character, hurt by) animal-like creatures in a colosseum. Characters are taken by surprise in a tunnel full of creatures armed with 'laser-beam guns'. A young character mourns his dead father who has been decapitated (he holds his father's head, concealed by a helmet, in his hands). All of these scenes/sequences are either brief or handled with a mild intensity.
Drugs/Alcohol: Very mild - Someone tries to sell one the main characters "death sticks" (presumably a type of drug) which he declines and advises the seller (through mind-control) to "go home and re-think his life". It is unlikely that this will be of any concern to children.
Overall: Mild themes. There are some moderate concepts addressed such as dealing with the loss of a parent which may well lead to questions being asked by more inquisitive children. These are, however, handled briefly and within the context of fantasy. Younger children may also be frightened by the creatures in the colosseum.